New study from Taiwan, below [1].
Of interest, since the findings are somewhat different from past U.S. studies.
However, I recognize that the subject is a downer. After all, who wants to contemplate dealing with a second cancer? Some might want to skip this post. On the other hand, some will want to understand the risk. & note that if a small risk doubles, it remains a small risk.
When I had salvage radiation over 12 years ago, I was told that my chance of colon cancer would rise after 5 years. After 10 years, I reluctantly had a colonoscopy (unrelated to PCa). The pictures were reassuring - the tissue looked very healthy: remarkably so, I felt. And it occurred to me that many of the supplements I use might help prevent colon cancer. & perhaps other cancers. & might even slow the progress of occult cancer. Maybe I will be unlucky, but I feel that I am doing something to level the playing field.
Perhaps addressing chronic sub-clinical inflammation is the answer (which has been one of my targets). See my series of posts on inflammation.
Taiwanese "Men with PCa had a trend of lower risk of developing overall SPMs {second primary malignancies} compared to those without PCa ..." 5% less!
Based on a population of 30,964 men with PCa, diagnosed between 2000 & 2011. Controls: "frequency-matched with an individual without PCa, based on age, comorbidity, and index year"
I don't know how much screening goes on in low-risk Taiwan, but in a country without any screening, all cases would be advanced at diagnosis & mortality would be grim. Little time for a second cancer to be identified. In an over-screened population such as the U.S., with prompt treatment, survival statistics would be very good, with perhaps ample time for a 2nd malignancy to be diagnosed. {The U.S. PCa "10-year relative survival rate is 99.7%" [4] Thanks largely to all the Gleason 3+3 cases.}
So men with PCa in Taiwan get fewer secondary cancers. However: "In contrast, these patients had a significantly higher risk of thyroid cancer" than men without PCa. Adjusted sub-hazard ratio = 4.62.
The PCa-thyroid connection is something I have discussed before. Some studies support it, but there is a paper [5] that suggests that both cancers are over-diagnosed (and over-treated) & that men who have both are probably over-screeners (blame the victim). After all, what possible connection could there be?
For me, the connection might be iodine deficiency. I became aware of the possible importance of iodine in the prostate 12 years ago & started using it. Prior to this, I had visited a hand surgeon who diagnosed a painful trigger finger as being caused by Dupuytren's contracture. He offered no treatment - or rather, advised against surgery, which is rarely helpful.
The diagnosis & the start of iodine use was one of those serendipitous timings that sometimes occur. The overgrowth of connective tissue in my palm disappeared at about the same rate as it had grown (it had been growing pretty fast, so was almost all gone in 12 months.)
The iodine deficiency / PCa & Dupuytren's connections are mentioned in Dr. Brownstein's "Iodine: Why You Need It, Why You Can't Live Without It", but are rarely discussed elsewhere.
Anyway, if the Taiwanese are not over-screening, the PCa-thyroid cancer statistic might not be a screening anomaly after all.
Dr. Myers ruefully refers to radiation as "the treatment that keeps on giving." My urologist, speaking of bladder issues in PCa cases, told me that he spent a lot of time "cleaning up" after radiologists. (Are oncologists even aware of such problems? Or patients?)
"Further analyses indicated that PCa patients who received radiation therapy (RT) had an increased risk of overall SPMs, hematologic malignancies, esophageal cancer, liver cancer, lung cancer, and urinary bladder cancer compared with those who did not receive RT."
Why? Many men who could opt for surgery are persuaded that radiation is better, but older men with serious comorbidities usually don't have the option of surgery. The Taiwan finding might reflect that - although "urinary bladder cancer" may be due to radiation, of course.
[2] (2016 - U.S.) "Risk of second primary malignancies among cancer survivors in the United States, 1992 through 2008." (not PCa-specific)
"A cohort of 2,116,163 patients was identified, 170,865 of whom (8.1%) developed a second primary malignancy."
Thankfully, no special mention of PCa in the Abstract, but the full text would have the PCa details.
[3] (2013 - U.S.) Does ADT affect risk?
"Our results suggest that among men with localized prostate cancer, ADT is not associated with an increased risk of second primary malignancies."
[4] (2014 - U.S.)
"A population-based cohort of 441,504 men who were diagnosed with prostate cancer between 1992 and 2010 was identified ..."
"The risks of leukemia and cancers of the oral cavity and pharynx, esophagus, stomach, colon and rectum, liver, gallbladder, pancreas, lung and bronchus, and larynx were significantly lower."
"Conversely, these patients had a greater risk of bladder, kidney, and endocrine and soft tissue cancers."
"Men who received treatment with radiation therapy (external-beam radiation therapy) had long-term increases in their risk of bladder cancer (SIR = 1.42) and rectal cancer (SIR = 1.70) risk compared with who did not receive radiation ..."
"Men with early onset prostate cancer had a ... higher risk of ... thyroid cancer (SIR = 1.63 ...) compared with men in the general population and in contrast to men who were diagnosed at older ages (... thyroid cancer, SIR = 1.02 ...)"
"Overall, we observed that prostate cancer survivors had a 40% lower risk of developing a second primary cancer compared with the general US male population. Specifically, they had a lower risk of developing leukemia and cancers of the oral cavity and pharynx, esophagus, stomach, colon and rectum, liver, gallbladder, pancreas, lung and bronchus, and larynx."
[5] PCa & Thyroid Cancer.
[5a] (2015 - U.S.)
"Prostate and thyroid cancers represent two of the most overdiagnosed tumors in the U.S. Hypothesizing that patients diagnosed with one of these malignancies were more likely to be diagnosed with the other, we examined the coupling of diagnoses of prostate and thyroid cancer in a large U.S. administrative dataset."
"There is a significant association of diagnoses with prostate and thyroid cancer in the U.S. In the absence of a known biological link between these tumors, these data suggest that diagnosis patterns for prostate and thyroid malignancies are linked."
[5b] (2014 - Zurich, Switzerland)
"When stratified by treatment, the highest {standardized incidence ratio} was observed for thyroid cancer (3.57 ...)" (in PCa cases)
[5c] (2005 - U.S.) Here is an interesting PCa-thyroid connection. It relates to thyroid- stimulating hormone (TSH).
"The effect of Gleason score on TSH level was significant ... and independent of the effect of age ..."
"We propose that the high serum TSH levels in men with Gleason 8 prostate cancer is a result of the elaboration of TSH by cancer cells. Bone mineral density in the face of normal levels of thyroid hormone depends on an intact response to TSH, which ordinarily suppresses both osteoblast and osteoclast differentiation, thereby exerting control over bone remodelling. However, with abnormally high TSH levels this process may become deranged, promoting the development of bone metastases. If TSH production by prostate cancer cells could be suppressed, the incidence of bone metastases might be reduced."
-Patrick
[1] journals.plos.org/plosone/a...
[2] ncbi.nlm.nih.gov/pubmed/273...
[3] ncbi.nlm.nih.gov/pubmed/232...
[4] ncbi.nlm.nih.gov/pmc/articl...
[5a] ncbi.nlm.nih.gov/pmc/articl...
