To SRT or not to SRT? That is the question posed by my first visit with a radiation oncologist to discuss salvage radiation therapy after ten months of gradually rising PSA scores. He doesn’t think the answer is simply to fire away with the ray guns and explained why.
A little background: I was diagnosed in February 2015 with a Gleason score of 3+4 = 7 and had a prostatectomy performed by a top surgeon at UCSF in April 2015. The pathology report showed no extra-capsular extension, no seminal vesicle invasion, no lymph node involvement, no cancerous surgical margins (although there was some benign prostatic tissue left at the surgical margin).
In February 2016, my PSA first became detectable and since then has climbed to 0.129 ng/ml. There is still time for “early” salvage radiation therapy. Although early salvage radiation therapy has been shown to benefit many patients, there are some reasons to suspect it may not do much for me.
First, despite favorable results on other factors, the pathologist did report the presence of tertiary Gleason pattern 5 cells in the otherwise 3+4 tumor.
My RO and others take the presence of Gleason 5 very seriously, suggesting that whether it’s called 3+4+5 or 3+5, it’s perhaps time to recognize 7 with grade 5 present as high-risk rather than intermediate-risk cancer. See, e.g., Gleason Pattern 5 Is the Strongest Pathologic Predictor of Recurrence, Metastasis, and Prostate Cancer-Specific Death in Patients Receiving Salvage Radiation Therapy Following Radical Prostatectomy
. Gleason Pattern 5 could behave more like, or even worse than, Gleason Score 8 (4+4) in terms of biochemical recurrence, distant metastases, mortality, and, most importantly for me at this moment of decision, response to salvage treatment.
In my RO’s estimation, this suggests that, although SRT is my only remaining hope of a cure, this adverse pathology suggests my chances of a cure from SRT are not great—not 80%, not 50%, but quite a bit lower – perhaps 30% or even less.
Samples of my cancerous tissues were sent down to GenomicsDX in March to obtain a calculation of my Decipher score. According to this genomic analysis, without followup treatment, my odds of distant metastasis within five years are 6.6% and my risk of prostate cancer-specific death within 10 years is 6.3%. The Decipher report from GenomicsDX classifies my risk as intermediate and indicates that I “may” benefit from SRT.
However, the new PORTOS score, which my RO was able to get from GenomicsDX during our meeting last Thursday, was low – suggesting that I am unlikely to benefit from SRT. PORTOS stands for Post-Operative Radio Therapy Outcome Score and it is a new 24-gene analytic tool developed for the express purpose of finding a genetic signature that would identify which patients were likely to benefit from SRT and which would not. PORTOS was developed by Dr. Felix Feng, now at UCSF, and is the subject of a report published in this month’s Lancet Oncology. You can read more about
it on Tall Allen’s blog here
The retrospective test results reported in the Lancet article are eye-popping. PORTOS low scorers (which were ¾ of the group studied) derived on average no benefit from SRT. PORTOS high scorers (the other ¼) were substantially less likely to have metastasis at ten years if they had SRT compared to those who did not.
My RO is none other than Dr. Felix Feng who developed the PORTOS test so you might think he would be gung-ho about
advising me against SRT based on my low PORTOS. That is not what he said at all. Dr. Feng cautioned that PORTOS is a new test and requires further validation. Although the development of PORTOS is considered important because PORTOS is the first genomic test to determine the likelihood that a particular therapy will be effective against prostate cancer, it is a new test that requires further validation by other researchers to confirm its value in making clinical decisions. I suspect I am one of the first guys in this community to have a PORTOS score to consider.
Dr. Feng explained that I will have to decide for myself whether to proceed with SRT, depending on whether I am a glass half empty or glass half full person.
If I choose not to do SRT, the reasoning would be: 1) radiation causes side effects; 2) chances that radiation will cure me are low; 3) my Decipher score predicts that I only have a 6.6% chance of metastasis within five years even if I don’t do SRT; 4) the PORTOS genomic test predicts no benefit; and 5) my PSA is still quite low; it may settle down and, if it doesn’t, hormone therapy is an option down the road.
If I decide to go ahead with radiation, the rationale would be: 1) it’s my only chance for a cure; 2) I’m overall very healthy and could live plenty long so even a small chances of a cure is worth quite a bit to me; the Decipher test’s estimate of the risk of metastasis would no doubt be a lot worse at ten years; 3) the PORTOS score is too new to serve as a basis of decision, and 4) the side effects are not likely to be all that bad.
On the way home across the Bay Bridge returning to our beloved Oakland, my wife and I puzzled over whether I am a glass half empty or glass half full person and how, if at all, my inclinations towards half empty or half full glasses apply to this choice. Apparently, evidence-based decision-making still involves hunches and consultations with animal spirits.
P.S. If you are interested in an earlier thread about
my negative Gallium 68 PET/MRI scan, that thread is over here
Dx 2/1/15 (age 65)
8/14 PSA 6.4
2/15 PSA 5.45 (8% free)
Bx 1/26/15 8/12 cores; 3 cores G7 (3+4); 5 cores G6 (3+3)
RALP (UCSF) 4/8/15; nerves spared; sling made from vas
Pathology: G7 (3+4, tertiary 5); ECE-, SM-, LN-, SV-; PNI+
Decipher: 6.6% 5-yr metastasis; 6.3% 10-yr PCa mortality
PSA 5/15, 8/15, 11/15: <0.015; 2/16 .031; 5/16 .053; 8/16 .107; 9/16 .129
10/16 Ga68-PSMA PET/MRI: clean