Saturday, July 10, 2021


Many patients read "sciency" sounding posts on the internet and youtube videos. They follow poor advice, thinking it is scientific. I compiled this checklist for the patient who is wondering if what he saw is science or fake news. Often, it looks like science because there are a lot of footnotes. I adapted a document I saw on Twitter.  I have added to it and added some explanation below:

Some Characteristics of Pseudoscience

1. Is UNFALSIFIABLE (can’t be proven wrong); makes vague or unfalsifiable claims.

2. Relies heavily on ANECDOTES, personal experiences, testimonials, “professional” opinions, and preclinical (test tube or animal) studies. IGNORES “LEVELS OF EVIDENCE,” and GRADE given by professional consensus.

Note: For every 10,000 compounds screened->250 (2.5%) are entered into a preclinical study 
-> 5 (2%) are tested in clinical trials -> 1 gets FDA approval

3. CHERRY PICKS confirming evidence while ignoring/minimizing disconfirming (especially higher level) evidence.

4. Uses TECHNOBABBLE: Words that sound scientific but don’t make sense.

5. Lacks PLAUSIBLE MECHANISM: No way to explain it based on existing knowledge, or deficient evidence for the proposed mechanism.

6. Is UNCHANGING: doesn’t self-correct or progress.

7. Makes EXTRAORDINARY/EXAGGERATED CLAIMS with insufficient clinical evidence.

8. Professes CERTAINTY; talks of “proof” with great confidence. Ignores statistical confidence intervals and power.

9. Commits LOGICAL FALLACIES: Arguments contain errors in reasoning.

10. Lacks PEER REVIEW: Goes directly to the public (e.g. YOUTUBE videos, blogs, direct-to-patient presentations only), avoiding scientific scrutiny.

11. Claims there is a CONSPIRACY (e.g., Big Pharma/FDA conspiracy) to suppress their ideas.

12. OVERSIMPLIFIES biochemistry (e.g. alkaline water, reducing sugar intake, antioxidants or anti-inflammatories will slow cancer)

13. Ignores INTERACTIONS with other substances, bioavailability, biochemical feedback effects, microbiome, substance purity, or adulteration

14. Claims “causation” when only “ASSOCIATION” has been demonstrated. (See the Bradford-Hill checklist) 

15. LACK OF DISCUSSION of potential biases, missing confounding variables, effects that may have changed over time and/or with improved technology.

16.  INAPPROPRIATE STATISTICS AND RESEARCH METHODS. Non-valid endpoints or subset conclusions, lack of pre-announced endpoint and subsets, lack of power to detect endpoint within sample size and timeframe, poor choice of surrogate endpoint or subsets, "p hacking," biases in retrospective studies.

17. Failure to disclose CONFLICTS OF INTEREST or sponsors.

#15 and #16 require some explanation:

Surrogate endpoints: Ideally, we would have long-term follow-up until death ("overall survival") for every trial. This is impractical, particularly for prostate cancer that has a very long natural history. ICECAP has identified "metastasis-free survival" as an appropriate surrogate for overall survival in trials involving men with localized prostate cancer.  The appearance of metastases has been suggested as appropriate for men with recurrent PCa but requires validation. Biochemical recurrence-free survival is inappropriate. PSA doubling time is definitely inappropriate without a control group. Radiographic progression-free survival seems to be a good surrogate endpoint in men who are metastatic and castration-resistant (see this link and this one). If the pattern holds, PSA-based endpoints are inadequate (see this link and this one) and only metastasis-based endpoints are adequate. Typically, trials are only powered (have enough sample size) to reliably detect differences in their primary endpoint.

Subset conclusions: Because there is only enough sample size to reliably detect differences in the primary endpoint, subset analysis is suspect. Using subset analysis, Spears et al. showed that men diagnosed on Mondays did not benefit from abiraterone - a ridiculous conclusion. They also showed that men diagnosed with metastases (M1) benefited while men diagnosed without metastases (M0) did not. Both conclusions are inappropriate. In the case of men without metastases, there were only 34 deaths among the 460 patients in the treatment group and 44 deaths among the 455 patients in the treatment group - not enough to prove a statistically significant effect with 95% confidence. However, with time, there may be enough deaths to achieve a statistically significant effect, so we have to be cautious about labeling it as ineffective in the M0 subgroup.

"P hacking" or "data-dredging"/positive results bias occurs when researchers do not announce before the study begins exactly which subgroups or variables will be looked at and which measures will be used to judge success or failure. They are going on a fishing expedition to find at least some variable or subgroup with statistically significant results. Because of random probabilities, if there are enough variables there will almost always be some that have statistically significant outcomes, like the "Monday diagnosis" subgroup above. Starting in 2000, all peer-reviewed journals required researchers to state upfront what they would be looking for. This made a large change in the number of positive results reported (see this link). Journals often would not print negative findings. In 2017, NIH and the FDA required the sponsors of all clinical trials listed in to provide results whether positive or negative. Policing and compliance are spotty.

Biases in retrospective studies and database analyses: Common biases are selection bias, ascertainment bias, lead-time bias, length bias, survivorship bias, confounding by unmeasured variables, and others.

Thursday, June 17, 2021

Lower salvage radiation dose - are outcomes the same?

A large randomized clinical trial, SAKK 09/10, found that a salvage radiation dose of 64 Gy over 32 treatments had equivalent biochemical outcomes compared to 70 Gy over 35 treatments.

They treated 350 patients from 2011 to 2014 at 28 hospitals in Germany, Switzerland, and Belgium. They were treated with either 3D-CRT (44%) or more modern radiation techniques. None had positive lymph nodes. Key patient characteristics were as follows:

  • Biochemically recurrent after prostatectomy (median PSA= 0.3 ng/ml)
  • Positive margins in 45%
  • Gleason score ≥ 8 in 18%
  • No detectable tumors

After 6.2 years of follow-up, outcomes were as follows:

  • Freedom from biochemical progression (FFBP) was enjoyed by 65% of those who got 64 Gy vs 73% of the 70 Gy group. This difference is not statistically different (p=0.11).
  • Local recurrences (only) occurred in 9% of the 64 Gy group vs 2% of the 70 Gy group. This difference is statistically significant (p= 0.005)
  • Regional recurrences (only) occurred in 11% of the 64 Gy group vs 17% of the 70 Gy group. This difference is not statistically significant (p= 0.11)
  • Distant recurrences (any) occurred in 15% of the 64 Gy group vs 15% of the 70 Gy group.
  • In an earlier report, acute urinary toxicity of Grade 2 or greater occurred in 14% of the 64 Gy group vs 18% of the 70 Gy group (not different)
  • In an earlier report, acute rectal toxicity of Grade 2 or greater occurred in 17% of the 64 Gy group vs 18% of the 70 Gy group (not different)
  • Late urinary toxicity of Grade 2 or greater occurred in 29% of the 64 Gy group vs 30% of the 70 Gy group (not different)
  • Late rectal toxicity of Grade 2 or greater occurred in 12% of the 64 Gy group vs 22% of the 70 Gy group (different)
  • Patient-reported outcomes were not different between the two dose regimens.

Oncological Outcomes

The stated purpose of SAKK 09/10 was to detect a difference in 6-year FFBP, and they detected no difference. But is that enough to change practice? The ICECAP working group cautions  that 5-year metastasis-free survival, but not biochemical recurrence-free survival, is a good surrogate endpoint when overall survival would take too long to obtain in trials of primary therapy for localized prostate cancer. For trials of salvage therapy of recurrent prostate cancer after prostatectomy, some early analysis suggests that the 5-year occurence of distant metastases may be a good surrogate endpoint. 6-year FFBP used in this trial is probably not a good surrogate endpoint.

Focusing our attention on the actual cancer progression instead of just PSA progression, we see that the higher dose did significantly better at preventing local progression of the cancer. If the trial were to run 15 years, we might see a very meaningful difference between the curative powers of the two dose regimens. Furthermore, as shown in the SPPORT trial, salvage treatment of pelvic lymph nodes, even when none is detectable, may slow progression or possibly cure some patients with regional micrometastatic progression. 

There may be other ways to improve outcomes:
  • Using the expanded prostate bed delineation guidelines may improve local control.
  • As PSMA PET/CT becomes more widely available, it will be possible to detect more loco-regional cancer for boost doses, and eliminate salvage treatment from patients who already have small distant metastases. 
  • The use of genomic tests, like Decipher, may aid in selecting patients in whom higher doses are needed. In a subset analysis, among Decipher "high risk" patients, FFBF was 51% for 70 Gy vs 39% for 64 Gy patients.
  • There is a clinical trial at UCLA that will determine whether raising the biologically effective dose (BED) using SBRT (34 Gy/ 5 fractions) gives good outcomes compared to historical controls. The BED is equivalent to 85 Gy if given in fractions of 1.8 Gy.
  • There is a clinical trial in France that will determine whether adjuvant hormone therapy intensification with Erleada improves results.
  • Keeping in mind that very few patients in this trial had Gleason scores of 8-10, and none had detectable gross tumors at or near the prostate, those patients may still be good candidates for dose intensification (as well as adjuvant ADT).

Toxicity Outcomes

If there is no cost to the patient in terms of increased toxicity, there is no reason not to increase the dose. The patients were unable to detect a difference in urinary, rectal, or sexual outcomes. There was a difference in physician-reported late-term rectal toxicity that deserves further attention.

Compared to acute urinary toxicity, late-term urinary toxicity is about twice as bad in both dosing regimens, although the ratings are not different between regimens. Compared to acute rectal toxicity, late-term rectal toxicity was 29% lower for the 64 Gy dose group, but marginally higher for the 70 Gy dose group. The authors believe that rectal dose constraints could be tightened with IMRT.

For comparison, MSK reported that using 70 Gy as a salvage dose, late-term urinary toxicity (Grade≥2) was 17% (vs 30% in this trial) and late-term rectal toxicity (Grade≥2) was 5% (vs 22% in this trial). They also reported that IMRT improved rectal toxicity over 3D-CRT, while no difference was observed in this trial.

The reason for these atypical results is mysterious, although physician-reported toxicities are notoriously unreliable.

So, lacking more reliable endpoints and considering that patients did not notice any difference in their quality of life based on dose intensification, the decision on what dose to use is best based on a discussion with the radiation oncologist.

Thursday, June 3, 2021

Brief, intense radiation and hormone therapy for very high risk prostate cancer

As we've seen, brachy boost therapy seems to have the best oncological results for men with very high-risk prostate cancer. But brachy boost therapy entails 20-25 external beam radiation treatments plus the invasive placement of radioactive seeds or needles plus at least 18 months of testosterone suppression. While the oncological results are excellent, with about 80% cure rates, there is significant risk of serious late-term urinary retention. In some men, testosterone never fully recovers.

McBride et al. reported the early results of the AASUR trial. The goal of the trial was to find a treatment with equivalent oncological outcomes, but one that is easier on the patient, with less risk of long-term toxicity. They recruited 64 patients at 4 top institutions (Memorial Sloan Kettering, Johns Hopkins, University of Michigan, and Thomas Jefferson University). All patients were "very high risk," defined as:

  • any Gleason score (GS) 9 or 10, or
  • 4 or more cores of GS 8, or
  • 2 high-risk features (stage T3/4, GS 8, or PSA>20)
  • No metastases (N0, M0)

Patients were treated with:

  • SBRT (7.5-8.0 Gy x 5 treatments)
  • 6 months of Lupron, Erleada, and Zytiga

After 30 months of follow-up:

  • 90% were free of biochemical failure
  • Median PSA at the last follow-up was 0.1
  • PSA remained undetectable in 40%
  • Testosterone rose to non-castrate levels at a median of 6.5 months after hormone therapy ended, and almost all rose to >150 ng/dl
  • 23% experienced transient serious toxicities, mostly hypertension
  • Quality of life scores at 1 year held for urinary and rectal domains but declined in sexual and hormone domains.

How do these results compare to other trials of radiation+ADT in high-risk patients?

Lin et al. used whole pelvic IMRT with an SBRT boost to the prostate and 2 years of ADT in 41 high- and very high-risk patients. With 4 years of follow-up, they reported 92% biochemical recurrence-free survival (bRFS).

Hoskin et al. used high dose rate brachytherapy as a monotherapy in 86 high-risk patients. Most (80%) had adjuvant ADT for a median of 6.3 months (range 1-40 months). With 4 years of follow-up, they report 87% biochemical recurrence-free survival (bRFS) among high-risk patients.

Zapatero et al. reported the results of the DART 01.03 GICOR trial of escalated dose IMRT with either short-term (4 months) or long-term (28 months) ADT. There were 185 high-risk patients with about half getting each ADT protocol. About a quarter received simultaneous radiation of their pelvic lymph nodes. With 5 years of follow-up, they report 76% bRFS among high-risk patients who got short-term ADT and 88% bRFS among high-risk patients who got long-term ADT.

Alan Pollack reported early results of the NRG Oncology 0534 or SPPORT randomized clinical trial at the ASTRO meeting in 2018.  Approximately 600 patients with a biochemical failure after prostatectomy were treated with whole pelvic salvage radiation. They all received 4-6 months of adjuvant ADT. With 5 years of follow-up, they reported 89% bRFS. (They defined this second bRFS as nadir +2.0, as in radiation trials.)

This table summarizes these trials:


SBRT boost













2.5 yrs

4 yrs

4 yrs

5 yrs

5 yrs

5 yrs




SBRT boost




(dose escalated)


(dose escalated)



area over 



Whole pelvic 

±SV (if MRI+)

• SV

• 27% 

whole pelvic

• SV

• 19%

 whole pelvic

Whole pelvic





93% ADT

80% ADT




Duration of 



6 months

2 yrs

6.3 months

4 months

28 months

4-6 months



78% HR

22% VHR












HR=high risk VHR=very high risk SV=seminal vesicles bRFS=biochemical recurrence-free survival: PSA stayed lower than nadir+2.0 ng/ml

2.5 years of follow-up is too early to draw valid conclusions. We see that most of the trials had higher bRFS even with much longer follow-up; however, only AASUR recruited very high-risk patients exclusively. ICECAP has shown that only metastasis-free survival is a valid surrogate endpoint for overall survival. A trial on high-risk patients will have to run for 8-10 years to collect a sufficient number of metastases to draw valid conclusions, so we can only look at this as an early signal.

Treatment of Pelvic Lymph Nodes

We know that the time to be able to see the first few cancerous pelvic lymph nodes is often several years, so 2.5 years of follow-up tells us little. The newly approved PSMA PET scans will be able to rule out the larger metastases (>5 mm), but will never be able to find metastases smaller than that. Waiting for visibility to make the decision to treat is a bad idea. By the time some lymph nodes are large enough or rapidly growing, the risk of spread outside the pelvic lymph node drainage area increases, and the hope of a cure may vanish.

The PSMA PET/CT is nevertheless worthwhile. While a negative scan does not change the treatment decision, a positive scan may detect occult metastases or pelvic lymph nodes that may benefit from a higher spot dose and more intense or longer hormone therapy.

We rely on validated formulas to tell us the probability that there are microscopic pelvic lymph node metastases. Two of the popular formulas are the Roach Equation (discussed here) and the Yale Formula (discussed here).

There is a risk of overtreatment. Many high-risk patients will never require pelvic lymph node treatment, and we are awaiting evidence (RTOG 0924) that such treatment will improve survival. As we have seen, bRFS is improved.

However, the only risk is that toxicity will be higher when the whole pelvis is treated. Murthy et al. showed that even at higher doses of pelvic lymph node radiation, there was no increase in acute toxicity, late gastrointestinal toxicity, and no deterioration in patient-reported quality of life scores.

Arguably, 25 extra IMRT treatments to the pelvic lymph nodes represent a patient inconvenience over the 5 SBRT prostate-only treatments. In the UCLA and Sunnybrook high-risk SBRT trials (discussed here), the pelvic lymph nodes may be treated (to 25 Gy) within the same 5 treatments. So far, with limited follow-up, cancer control is high and toxicity is low.

Hormone therapy intensification

The DART 01.05 GICOR trial proved that long-term (28 months vs 4 months) ADT improves survival in high-risk patients even when treated with dose-escalated IMRT. Nabid et al. proved that 18 months is often as good as 36 months. AASUR suggests that by including both Zytiga and Erleada, the duration of hormone therapy can be shortened. But the sexual and hormone quality of life did diminish. This raises questions that can only be answered in an expanded randomized clinical trial:

  • Are all 3 medications (Zytiga, Erleada, and Lupron) necessary for the benefit? The ACIS trial found that adding Erleada increased radiographic progression-free survival in mCRPC patients. There was no such synergy found in adding Xtandi to Zytiga in this non-randomized trial.
  • Do they add much to Lupron alone if whole pelvic radiation is given?
  • Does Lupron alone for, say, 9 months, with whole-pelvic SBRT (as in the UCLA trial) afford the same benefit with less toxicity? And would Orgovyx instead of Lupron allow for earlier testosterone recovery?
  • Can genomics (Prolaris or Decipher of biopsy tissue) identify patients who might benefit from the combined hormone therapy?

Sunday, May 23, 2021

Abiraterone+docetaxel+ADT for newly diagnosed metastatic men beats docetaxel+ADT (or abiraterone+ADT)

The first results of the long-awaited PEACE-1 randomized clinical trial (RCT) are in. They randomized newly diagnosed metastatic men to either prostate radiation or abiraterone or standard-of-care (SOC). SOC included docetaxel for many of the men.

Radiographic progression-free survival increased by 2.5 years (from 2.0 to 4.5 yrs) with the addition of abiraterone to docetaxel. Time to castration resistance increased by 1.7 yrs (from 1.5 to 3.2 yrs). 

The full results will tell us how much the prostate radiation adds, and the effect on overall survival. The analysis by metastatic burden will be important too. Meanwhile, docetaxel+abiraterone+ADT should be considered the new standard of care.

How does this combination therapy compare to previous RCTs for docetaxel or abiraterone?

Because the STAMPEDE RCTs for docetaxel and abiraterone occurred at about the same time, 566 patients were randomized to one or the other. Sydes et al. reported the outcomes after a median of 4 years of follow-up. 
  • Abiraterone reduced PSA more quickly, as reflected in "failure-free survival" (time to PSA increase, clinical progression, or death) and "progression-free survival" (time to first "failure" event, excluding PSA). 
  • Those who received docetaxel first soon caught up. There were no significant differences in "metastasis-free survival," "prostate cancer-specific survival," "overall survival," or "time to the first skeletal-related event (pain or fracture)"
  • Serious toxicity (Grade 3 or greater) was also equal: 50% for docetaxel, 48% for abiraterone.

The STAMPEDE researchers (the STOPCAP group) did a meta-analysis of the STAMPEDE trials that concluded that abiraterone probably had a greater effect than docetaxel, but unlike the analysis above, it was not a direct comparison. They concluded that either should be recommended.

The other RCTs for metastatic hormone-sensitive prostate cancer (mHSPC) included STAMPEDE- abiraterone, LATITUDE- abiraterone, STAMPEDE-docetaxel, CHAARTED-docetaxel.GETUG-AFU-15(docetaxel) did not detect a difference in survival from the early use of docetaxel. 30% had prior treatment. There were differences in the populations studied in each trial that should be understood.

LATITUDE screened for more advanced patients - 80% were "high risk." High risk was defined by having 2 of 3 "high-risk" features, either: Gleason 8-10, or ≥ 3 bone metastases or visceral metastases. About half had performance status of 1 or 2 ("0" is the best performance status).

CHAARTED started by recruiting only patients with a high burden of metastases. But only 73% were de novo, meaning 27% had been previously treated before they entered the trial. They later opened the trial to men with fewer metastases and ended up with a small group (27%) of low burden de novo patients. They defined "high burden" as visceral metastases or ≥ 4 metastases with at least 1 outside the axial skeleton.

The two STAMPEDE trials recruited almost entirely (95%) de novo patients. 56% were "high burden" by the CHAARTED definition. 52% were "high risk" by the LATITUDE definition. 26% had performance status of 1 or 2.

PEACE1 recruited only de novo metastatic patients, with excellent performance status. 57% had high-risk features by the LATITUDE definition.

The following chart shows how long it took for patients to progress on each of the early interventions. Complicating analysis, each trial used a slightly different definition of progression.

Time to "progression" following each early therapy




ADT alone

Trial notes


4.5 yrs

2.0 yrs

100% de novo, 100% perf. status 0, 57% high volume



Not reached (> 3.4 yrs)

2.0 yrs

94% de novo,26% perf.status 1 or 2, 55% high volume



2.8 yrs

1.2 yrs

100% de novo, 45% perf. Status 1 or 2, 80% high volume/high risk



3.1 yrs

1.7 yrs

95% de novo, 56% high volume



2.8 yrs

1.7 yrs

73% de novo, 65% high volume

* time to radiographic progression or death
time to first symptomatic event or death
§ time to symptoms or radiographic progression

While comparison is complicated, the extension of progression-free survival by 2.5 years by adding abiraterone to docetaxel alone is impressive. Docetaxel adds 1 - 1.5 years to progression-free survival over ADT alone. Abiraterone adds 1 - 1.5 years to progression-free survival over ADT alone.

Does docetaxel only benefit mHSPC patients with a high-volume of metastases?

This has stirred much controversy. Gravis et al. argue that the overall survival improvement from docetaxel was seen in CHAARTED only among men with high-volume metastases was a real biological effect (i.e., that high-volume PC is a different disease from low-volume PC, that responds differently to chemo). Armstrong argues for a biological difference. They acknowledge, however, that the small sample size of de novo men with low volume metastases (n=154) and their short follow-up (only 16% had died during the 48 months of follow-up) may be underestimating the benefit in the low volume, de novo subgroup. Remember that in CHAARTED, the low-volume subgroup was not recruited initially, so the follow-up is shorter in the group that needs the longer follow-up.

Clarke et al. argue that STAMPEDE is the more definitive trial because its sample size of mHSPC men with low-volume metastases was over twice as great (n=362) and the follow-up was longer (62% of the docetaxel patients had died during 78 months of follow-up). They did not find evidence of heterogeneity - low-volume PC responded just as much to chemo as high-volume PC. While the effect on low volume PC was similar, the statistical confidence in its effect did not meet 95% confidence. They attribute this to insufficient sample size (power). Suzman and Antonarakis agree that chemo should be offered to all mHSPC men, regardless of volume of metastases. It would seem that a meta-analysis combining the low-volume, de novo subgroups from both CHAARTED and STAMPEDE might be sufficiently powered to provide a more definitive answer. Patients wishing to understand why analyses of subgroups are controversial, may be amused by this analysis of STAMPEDE subgroups. The authors found that patients born on a Monday benefited the most from abiraterone, and it was statistically significant. while patients born on a Friday had the least benefit, and it wasn't statistically significant. They further found that men diagnosed on a Monday did not benefit from abiraterone, whereas men diagnosed on other days had a statistically significant benefit. These absurd findings are sometimes known as "p-hacking" or "data dredging." This interview discusses this error and the mistake of drawing biological inferences from statistical significance. Pre-specifying subgroups is one way to avoid such errors, but drawing conclusions from inadequately powered subgroups, while tempting, should be avoided. This controversy is reflected in the conflicting recommendations that constitute the standard of care.

The current NCCN guidelines state: "Docetaxel should not be offered to men with low volume metastatic prostate cancer, since this subgroup was not shown to have improved survival in either the ECOG study or a similar European (GETUG-AFU 15) trial." The current ASCO guidelines state: "Recommendation 1.2. For patients with low-volume metastatic disease (LVD) as defined per CHAARTED who are candidates for chemotherapy, docetaxel plus ADT should not be offered (Type: evidence-based, benefits outweigh harms; Evidence quality: high; Strength of recommendation: strong for patients with LVD)." On the other hand, the current AUA/ASTRO/SUO guidelines state: "15. In patients with mHSPC, clinicians should offer continued ADT in combination with either androgen pathway directed therapy (abiraterone acetate plus prednisone, apalutamide, enzalutamide) or chemotherapy (docetaxel). (Strong Recommendation; Evidence Level: Grade A) Canadian Urological Assn (CUA) guidelines state: "Docetaxel plus ADT may also be an option in patients with mCNPC/mCSPC with good performance status with low-volume disease (Level 2, Weak recommendation)." NICE (UK) guidelines state: "Offer docetaxel chemotherapy to people with newly-diagnosed metastatic prostate cancer who do not have significant comorbidities." European Urological Assn (EAU) guidelines state: "Based on these data, upfront docetaxel combined with ADT should be considered as a standard in men presenting with metastases at first presentation provided they are fit enough to receive the drug [1070]"

I personally believe that the STAMPEDE researchers make a stronger case pending better data from PEACE1.

It is also possible that genomics will allow better selection of patients for early chemotherapy. Hamid et al. examined tissue collected for the CHAARTED trial. They found a subtype called "Luminal B" that was associated with improved survival from chemotherapy. This finding has not yet been validated on an independent trial. Meanwhile, DECIPHER provides the test as part of its GRID analysis.

The major advantages of early chemo vs "saving it for later" are:
  • Longer survival advantage
  • Side effects are milder when patients are less debilitated from years of cancer
  • As many as 10 infusions (usually 6) can be given if it is well tolerated
  • Most patients are not resistant, so docetaxel can be repeated
  • If there is resistance, cabazitaxel can be given

Tuesday, May 18, 2021

New Guidelines for Salvage Radiation Dimensions

It has always been troubling that only about half of all salvage radiation treatments after prostatectomy failure are successful. Usually, only the prostate bed is treated. But sometimes recurrent patients (or those with persistently elevated PSA) receive salvage radiation to the pelvic lymph nodes as well, or subsequently. Radiation oncologists usually follow RTOG (now called NRG Oncology) guidelines on what constitutes the dimensions of the prostate bed and the pelvic lymph nodes.

Prostate Bed Coverage

Often, the cancer has only penetrated into the bed or fossa. This is especially suspected if there are significant positive surgical margins. The 2010 RTOG consensus guidelines were updated in 2020 by the Francophone Group of Urological Radiotherapy (GFRU) based on standard imaging (MRI and CT). Harmon et al. reported on 45 patients within the LOCATE trial who received a positive Axumin PET/CT upon recurrence or persistent PSA after prostatectomy.

  • 30 patients had cancer in the prostate fossa
  • The 2010 RTOG guidelines completely or partially missed cancer in 33% of the patients
  • The 2020 GFRU guidelines completely or partially missed cancer in 10% of the patients
The new GFRU guidelines are clearly superior in terms of oncological outcomes, but toxicity must be considered as well.

Pelvic Lymph Node Coverage

In 2020, NRG Oncology revised its previous 2009 RTOG pelvic lymph node coverage consensus guidelines based on MRI and PET scans. They recommended coverage as high as the aortic bifurcation or common iliac lymph nodes (whichever is higher, depending on patient anatomy), which is about the level of the L4-L5 vertebrae. The expanded coverage area extends down to the pre-sacral nodes at the bottom of vertebra S3. Harmon et al. also validated the expanded NRG Oncology guidelines based on Axumin PET/CT scans. They found:

  • There were 43 sites of cancer in the pelvic lymph nodes
  • The 2009 RTOG guidelines completely or partially missed 32% of the nodal cancers
  • The 2020 NRG Oncology guidelines completely or partially missed none of the nodal cancers

The SPPORT trial found that treating pelvic lymph nodes prophylactically improved outcomes, but wasn't necessary in patients with low PSA. This study did not examine the toxicity of the expanded coverage. The wider margins of the prostate bed will probably increase genitourinary toxicity. Careful contouring of the pelvic lymph node area to exclude bowel, bone, bladder, and muscle seems to prevent excess toxicity at the doses usually used (45-50.4 Gy). In one recent study of high-risk patients, a pelvic lymph node dose as high as 56 Gy was used without extra toxicity. Boosted site doses can also be utilized where PET/CT  or MRI has identified specific tumors. However, treatment should not be delayed until such tumors become apparent on imaging.