Monday, May 27, 2019

"If all you have is a hammer, everything looks like a nail"

It was called "instrument bias" by Abraham Maslow and Abraham Kaplan, but for present purposes, we'll call it "specialty bias" - over-reliance on the tool one is most familiar with. Kishan et al. conducted a survey among urologists ("Uros") and radiation oncologists ("ROs") concerning their opinions about how best to treat high-risk patients in various situations from initial treatment to recurrence after initial treatment. They tabulated responses from:

  • 846 ROs and 407 Uros
  • 63% of ROs and 96% of Uros practiced in the US; the rest mainly in Australia and NZ
  • They had a median of over 10 years of experience
  • 41% of ROs and 51% of Uros were in private practice


Initial Treatment of High Risk Patients

ROs were 5 times more likely to believe that initial treatment with radiotherapy (RT) with androgen deprivation therapy (ADT) and with local salvage therapy, if needed, was preferred. They were also twice as likely to believe that it offered the patient equivalent outcomes as radical prostatectomy (RP) and salvage radiation (SRT), if needed. Uros were 4 times more likely to believe that RP ± SRT was the preferred treatment. Only 29% believed that RT had a place in initial treatment.


Preferred Initial Treatment
RO
Uro
RP±SRT
18%
71%
RT+ADT±local salvage
30%
6%
No preference
52%
23%

The "right" answer is...

Currently, the American Urological Association (AUA) and the American Society of Radiation Oncologists guidelines state:
"Clinicians should recommend radical prostatectomy or radiotherapy plus ADT as standard treatment options for patients with high-risk localized prostate cancer. (Strong Recommendation; Evidence Level: Grade A)"

NCCN guidelines also list both as options. They note, however:
"A large, multicenter, retrospective cohort analysis that included 1809 men with Gleason score 9–10 prostate cancer found that multimodality therapy with EBRT, brachytherapy, and ADT was associated with improved prostate cancer-specific mortality and longer time to distant metastasis than either radical prostatectomy or EBRT with ADT. In addition, an analysis of outcomes of almost 43,000 men with high-risk prostate cancer in the National Cancer Database found that mortality was similar in men treated with EBRT, brachytherapy, and ADT versus those treated with radical prostatectomy, but was worse in those treated with EBRT and ADT . (MS25)
This can only be decided definitively by a randomized clinical trial, but given the difficulties of recruiting for such a trial, patients must make the decision based on lower level evidence.

Adjuvant RT (ART) and SRT for High-Risk Patients after RP

ROs were 2.7 times as likely to advocate for ART with undetectable PSA, and were twice as likely to believe that ART is underutilized. Conversely, Uros were 2.5 times more likely to approve of waiting until PSA has risen to 0.2 ng/ml. Most believed it is utilized appropriately (it is seldom utilized in this situation) or overutilized. About 2 in 5 ROs and Uros were OK with early SRT.

Two-thirds of ROs thought SRT was appropriate with 2 consecutive rises, or at any detectable level or any level under or equal to 0.1. Less than half of Uros held that belief. ROs were more likely than Uros to believe that SRT is underutilized.


ART Appropriate
RO
Uro
With undetectable PSA
43%
16%
Early SRT with detectable PSA < 0.2 ng/ml
42%
43%
Delayed SRT with PSA ≥ 0.2 ng/ml
16%
41%


ART Under/Over-Utilized
RO
Uro
Underutilized
75%
38%
Appropriately utilized
21%
43%
Overutilized
4%
19%


Lowest PSA at which SRT is Appropriate
RO
Uro
Detectable
15%
7%
≤ 0.1
21%
19%
At least 0.2
29%
35%
At least 0.4
4%
12%
At least 1.0
1%
7%
At least 2 consecutive rises
30%
20%


SRT Under/Over-Utilized
RO
Uro
Underutilized
65%
43%
Appropriately utilized
34%
52%
Overutilized
1%
5%

The "right" answer is...

Guideline Statement 2. Patients with adverse pathologic findings including seminal vesicle invasion, positive surgical margins, and extraprostatic extension should be informed that adjuvant radiotherapy, compared to radical prostatectomy only, reduces the risk of biochemical recurrence, local recurrence, and clinical progression of cancer. They should also be informed that the impact of adjuvant radiotherapy on subsequent metastases and overall survival is less clear; one of three randomized controlled trials that addressed these outcomes indicated a benefit but the other two trials did not demonstrate a benefit. However, these two trials were not designed to identify a significant reduction in metastasis or death with adjuvant radiotherapy. (Clinical Principle)
 Guideline Statement 3. Physicians should offer adjuvant radiotherapy to patients with adverse pathologic findings at prostatectomy including seminal vesicle invasion, positive surgical margins, or extraprostatic extension because of demonstrated reductions in biochemical recurrence, local recurrence, and clinical progression. (Standard; Evidence Strength: Grade A)
Guideline Statement 8. Patients should be informed that the effectiveness of radiotherapy for PSA recurrence is greatest when given at lower levels of PSA.  (Clinical Principle) 
"...patients should be advised that if recurrence is detected without evidence of distant metastases, then RT should be administered at the earliest sign of PSA recurrence ..."
The 2019 NCCN guidelines state:
Indications for salvage RT include an undetectable PSA that becomes subsequently detectable and increases on 2 measurements or a PSA that remains persistently detectable after RP. Treatment is more effective when pre-treatment PSA is low and PSADT is long.


Salvage for High-Risk Patients after RT

About 2/3 of Uros believed that RP and Cryo are appropriate salvage therapies after biochemical recurrence following primary RT (when imaging was negative for distant metastases). Very few thought salvage radiation or other ablation therapies were appropriate. Among ROs, most approved of salvage RP, but sizeable minorities felt that salvage brachytherapy and salvage cryo was appropriate. About 1 in 5 thought salvage SBRT or salvage HIFU was appropriate.



Salvage therapies after RT failure
RO
Uro
RP
56%
66%
LDR brachytherapy
34%
6%
HDR brachytherapy
42%
10%
SBRT
20%
5%
Cryoablation
40%
69%
HIFU
21%
13%

However, 2/3 of both ROs and Uros and agreed that salvage after RT was not as effective as salvage after RP.


Is salvage after RT as effective as SRT after RP?
RO
Uro
No
64%
66%
Yes
36%
34%

And most of both groups believe that focal salvage is inferior to whole gland salvage after RT failure. But Uros were much more likely to hold this belief vs ROs.


Focal salvage=whole gland salvage?
RO
Uro
No
56%
75%
Yes
44%
25%


The "right" answer is...

NCCN guidelines state:

Salvage RP is an option for highly selected patients with local recurrence after EBRT, brachytherapy, or cryotherapy in the absence of metastases, but the morbidity (ie, incontinence, loss of erection, anastomotic stricture) is high and the operation should be performed by surgeons who are experienced with salvage RP. 
Brachytherapy can be considered in men with biochemical recurrence after EBRT. In a retrospective study of 24 men who had EBRT as primary therapy and permanent brachytherapy after biochemical recurrence, the cancer-free and biochemical relapse-free survival rates were 96% and 88%, respectively, after a median follow-up of 30 months.Results of a phase 2 study of salvage HDR brachytherapy after EBRT included relapse-free survival, distant metastases-free survival, and cause-specific survival rates of 68.5%, 81.5%, and 90.3%, respectively, at 5 years.
HIFU also has been studied for treatment of radiation recurrence. Analysis of a prospective registry of men treated with HIFU for radiation recurrence revealed median biochemical recurrence-free survival at 63 months, 5-year OS of 88%, and cancer-specific survival of 94%.
For a discussion of salvage therapies after RT, see this link. Salvage after RT is generally as effective or better than SRT after RP. Focal salvage is as effective as whole gland salvage in many cases.

What to do about specialty bias

It is not surprising that specialists are more knowledgeable about, and more favorably disposed to their own field (otherwise, they're in the wrong job). However, there are knowledge gaps even within their own field. Many patients expect their doctors to be knowledgeable about their own field, and to be able to compare it to other therapies. We have seen that this is an unrealistic expectation. Here are some recommendations for patients:

  • Don't expect a specialist to be knowledgeable outside his own field. Consult with a variety of specialists, if possible.
  • Remember that it is radiation oncologists, not urologists, who treat and follow-up on SRT for surgical recurrences. ROs are more experienced than Uros at SRT.
  • Salvage brachytherapy after RT recurrence is highly specialized - there aren't many practitioners with expertise. Salvage ablation and salvage SBRT specialists are even more rare. Patients should avoid salvage surgery due to its high morbidity.
  • Second opinions are critical. Finding specialists may involve travel, which may be precluded by cost/insurance limitations.
  • For patients who are inclined to research these topics themselves, they must be aware that the quality of research on all of these topics is low to moderate. There have been very few randomized clinical trials focussed on high risk patients, so we have to make informed judgments based on observational studies or single-arm, single-institution clinical trials in most situations. AUA, ASTRO and NCCN guidelines are updated and may be their best source of information (other than this blog 😉).

Focussing on physicians, the authors recommend interdisciplinary clinics, which might work well in academic centers. However, a substantial proportion of both ROs and Uros were in private practice. They also suggest continuing medical education, and cross-specialty training. Professional organizations typically do not currently require this. Uros do not typically attend ASTRO meetings, nor do ROs attend AUA meetings.

- with thanks to Dr. King for allowing me to see the full text and questionnaire.





Saturday, May 25, 2019

Is whole pelvic radiation needed for primary treatment of Gleason 9/10?

Whether whole pelvic radiation therapy (WPRT) is beneficial for men newly diagnosed with Gleason 9/10 (Grade Group 5) is controversial. There is an ongoing randomized clinical trial (RTOG 0924) that will have results by 2027 at the earliest, but it includes intermediate and high-risk patients, very few of whom will have Gleason 9/10. Two previous randomized clinical trials (RCTs) gave conflicting results: RTOG 9413 showed a benefit to WPRT combined with ADT started before and continued through radiation treatment, while GETUG 01 found no benefit. However, neither RCT delivered doses of radiation that would be considered adequate by today's standards (70 Gy vs 80 Gy).

Sandler et al. analyzed the databases of 12 major institutions that treated 1170 Gleason 9/10 patients between 2000 and 2013.

  • 299 received external beam radiation therapy (EBRT) boost to the prostate + WPRT
  • 435 received EBRT only to the prostate + a small margin around it
  • 320  received a brachytherapy boost (BBT) to the prostate + WPRT
  • 116 received BBT only to the prostate + a small margin around it
  • Patients were matched on age, T stage, PSA, Gleason score, and analyzed by ADT duration


After median follow-up of 5.6 years, 5-year biochemical recurrence-free survival (bRFS) was:

  • 88% for BBT+WPRT
  • 78% for BBT alone
  • 66% for EBRT+WPRT
  • 58% for EBRT alone
  • WPRT was significantly improved by BBT (Hazard Ratio = 0.5, p=0.02) but not by EBRT (HR=0.8, p=0.4))
  • Neither distant metastasis-free survival nor prostate cancer-specific survival were significantly improved by WPRT


In interpreting these findings, patients should discuss the following considerations with their radiation oncologists.

Lack of long-term follow-up

As we have observed before (see this link), it can take 15 or more years until over half of high risk patients have detectable metastases (by bone scan/CT) or have succumbed to prostate cancer. In this study, only 35% of those getting EBRT alone had been diagnosed with distant metastases, and only 23% had died of prostate cancer. The rates for all other groups were smaller. As the data mature, we expect that the now-evident and statistically significant differences in biochemical failure will eventually result in higher rates of metastases and mortality.

Lack of local control with EBRT only

ASCENDE-RT proved that prostate cancer is better controlled in high-risk patients by a brachytherapy boost than by EBRT alone. Local control (of cancer in the prostate) is obviously required because the high grade cancer easily progresses and metastasizes from the prostate.

Lack of regional control with surgery

As we have seen, prostatectomy, even when followed by radiation (see this link) seems to provide inferior cancer control compared to BBT with WPRT. This may be because the salvage radiation dose to the prostate bed (usually only 66-70 Gy) is inadequate compared to the primary radiation dose (see this link).

Inadequate coverage/detection of pelvic lymph nodes

In the present study, patients received WPRT to the standard pelvic lymph nodes. We have seen that this is inadequate to reach  the cancerous pelvic lymph nodes in over 40% of patients (see this link). Current methods do not allow us to find most of the cancerous lymph nodes (see this link). While PET scans are not yet FDA-approved for high-risk patients (as they are for recurrent patients), there are a few available in clinical trials.

Inadequate dose to pelvic lymph nodes

The dose to pelvic lymph nodes is often about 45-50 Gy given in 1.8 Gy increments. If it's true that perfect cancer control is achieved only with doses around 80 Gy, this treatment may be inadequate to control some of the larger lymph node metastases. This may be especially true because lymph node metastases are not well-oxygenated (hypoxic). As PET/CTs and PET/MRIs become available for high-risk patients, it may become possible to target known lymph node metastases with higher doses. Another fertile area for investigative research is radiosensitization with hyperthermia (see this link).

Toxicity

In RTOG 0534, late Grade 2 or worse gastrointestinal toxicity occurred in 7% of those receiving WPRT. While this is higher than the 2% experiencing this degree of toxicity with prostate-only EBRT treatment, it is nevertheless at a low level. In a large non-randomized, retrospective study comparing WPRT to prostate-only radiation, Parry et al. found no difference in the 3-year cumulative incidence of gastrointestinal and urinary toxicity among high risk and locally advanced patients.

Because we may never have more reliable data, patients and their radiation oncologists must make this decision based on this study and judgement for the foreseeable future.

note: Thanks to Amar Kishan for allowing me to see the full text.

Thursday, May 16, 2019

Two new advanced hormonal agents (apalutamide and enzalutamide) increase survival in metastatic hormone sensitive prostate cancer (mHSPC)

Erleada (apalutamide) has already been FDA-approved for use in non-metastatic castration-resistant prostate cancer (non-m CRPC), which affects relatively few men (remembering that metastatic was defined by bone scan/CT rather than PET scan). Now we have evidence that it increases overall survival in men with metastatic hormone-sensitive prostate cancer (mHSPC).

Chi et al. reported the early results of the TITAN randomized clinical trial at the ASCO meeting. The trial was conducted at 230 sites in the US and internationally. Patients received 240 mg/day of apalutamide (n=525) or placebo (n=527) plus ADT.

  • It was double blinded.
  • Prior treatments were allowed.
  • 8% had prior treatment for localized PC
  • 11% had prior docetaxel
  • 63% had high-volume metastases
  • 37% had low-volume metastases
After almost 2 years median follow-up, the outcomes were as follows:
  • Apalutamide reduced mortality by 33%
  • Apalutamide reduced radiographic progression or mortality by 52%
  • Benefit was seen in all subgroups (i.e, volume of metastases and prior treatments)
  • Time to docetaxel treatment was 61% longer in men getting apalutamide.
  • Because of the success, men getting placebo were allowed to get apalutamide
  • Grade 3 (serious) and grade 4 (life-threatening) toxicities were similar in both groups (41-42%)
  • Discontinuations due to adverse events were low in both groups (8% for apalutamide, 5% for placebo)
(Update 9/18/19 It has been FDA approved for this indication).

Xtandi (enzalutamide) has been FDA-approved since 2012 for mCRPC after docetaxel and since 2014 for mCRPC before docetaxel. Sweeney et al.  reported the results of the ENZAMET randomized clinical trial at the ASCO meeting and in the NEJM. 1,125 patients at 82 sites in Australia, New Zealand, Ireland, Canada, and the UK received 160 mg/day of enzalutamide plus ADT or a first-generation anti-androgen (AA) (bicalutamide, nilutamide, or flutamide) plus ADT. It was unblinded and was reported earlier than expected.
  • 3-year overall survival (3yrOS) was 79% for enzalutamide vs 72% for AA (Hazard Ratio = 0.66 - statistically significant)
  • For men with high volume metastases, 3yrOS was 71% for enzalutamide vs 63% for AA (Hazard Ratio = 0.74 - not statistically significant)
  • For men with low volume metastases, 3yrOS was 89% for enzalutamide vs 82% for AA (Hazard Ratio = 0.48 -  statistically significant)
  • For men who also planned to receive early docetaxel, 3yrOS was 73% for enzalutamide vs 74% for AA (Hazard Ratio = 0.91 - not statistically significant)
  • For men who did not plan to receive early docetaxel, 3yrOS was 83% for enzalutamide vs 70% for AA (Hazard Ratio = 0.51 - statistically significant)
Toxicity was higher for enzalutamide:
  • Serious adverse events occurred in 42% of those taking enzalutamide vs 34% for AA
  • Treatment discontinuation due to adverse events occurred in 33 patients taking enzalutamide vs 14 patients for AA
  • Adverse events were higher in those who had taken docetaxel
  • Fatigue was more common for men taking enzalutamide
  • Seizures occurred in 7 patients taking enzalutamide and no patients for AA
(update 12/16/2019: It has been FDA approved for this indication)

Based on these successes, I'm sure the FDA will fast-track approval for both drugs for this new indication, joining Zytiga and Taxotere. Because they are already available for another indication, insurance may allow them off-label even sooner. The cost for either is about $12,000 for a 30-day supply. It is unknown if they are any more effective than abiraterone, which is now available as a new formulation called Yonsa for about $10,000 per month.