Risk of second cancer following radiotherapy for prostate cancer: a population-based analysis

Abstract

BackgroundTo investigate the risk of second cancer and radiation induced second cancer following prostate cancer radiotherapy.MethodsWe compared men with radiotherapy only with those treated with radical prostatectomy only and those with radiotherapy after radical prostatectomy. Cumulative incidences of second cancers were calculated. Cox analyses were performed to identify determinants influencing second cancer incidence.ResultsNineteen thousand five hundred thirty eight patients were analyzed. Age and median follow-up differed significantly with radiotherapy only patients having the highest median age (70.3 years) and radical prostatectomy only patients the longest median follow-up (10.2 years). Ten-year cumulative incidence of second cancer was 15.9%, 13.2% and 10.5% for patients with radiotherapy only, radiotherapy after radical prostatectomy and radical prostatectomy only (p <0.0001). Increasing age and belonging to the radiotherapy only group were associated with a higher risk of second cancer—no significant increase was seen in radiotherapy after radical prostatectomy patients. A significantly higher rate of smoking related malignancies, like lung, bladder and non-melanoma skin cancer, was seen in radiotherapy only patients.ConclusionsNo clear increase in radiation induced second cancer was found in patients after radiotherapy for prostate cancer. Whereas the rate of second cancer was increased in radiotherapy only patients, no such increase was seen in patients with radiotherapy after radical prostatectomy. The increase of second cancer following radiotherapy only is highly likely to reflect advanced age and lifestyle habits and comorbidities.

Second cancers in radically treated Norwegian prostate cancer patients

“…Several previous studies comply with our findings and conclude that RT increases the risk of rectal cancer [8][9][10][11]21,22]. Kendal et al and Hegeman et al explained an apparently higher rectal cancer risk after RT with unmeasured confounding factors such as tobacco smoking [14,15], which is a wellknown risk factor for urinary bladder-and colorectal cancer [23][24][25]. Although we did not have access to smoking data, we find it reasonable to believe that the non-smokers were selected to prostatectomy more often than smokers.…”

“…Nevertheless, since our study did not demonstrate an increased incidence of colon cancer in the patients treated with RT, we believe that in-field late RT effects rather than smoking explain the observed higher rectal cancer risk following EBRT. Also corresponding with previous reports, we found a higher risk of urinary bladder cancer in the EBRT patients (Tables 2 and 3) [8,9,15,[20][21][22]26,27]. Patients treated with HRT-BT also had an increased risk of bladder cancer.…”

“…However, several of the studies showing increased risk of SC included patients from the 1970s and 1980s, and the findings may not be valid for contemporary clinical practice. Other studies have not shown a clear increased risk of cancer after RT for PC, and some authors explain the increased risk with confounding factors such as smoking [13][14][15]. Consequently, the effect of RT on the incidence of secondary cancers in PC patients is controversial.…”

Radiation‐induced sarcoma after radiation therapy for prostate adenocarcinoma

“…A meta‐analysis also indicated an increased risk of developing bladder, colorectal, and rectal cancers after radiation therapy . However, in a recent report by Hegemann et al ., the second malignancies that occurred in patients who received radiation therapy for prostate cancer were induced by cigarette smoking and not by radiation therapy . The meta‐analysis by Wallis et al .…”

Common dermatology questions and answers about the radiation treatment of skin cancer in the modern era

“…A literature review was undertaken of second primary neoplasms (SPNs) following RT in cancer patients and is tabulated in Table 3. [8][9][10][11] A reasonable way forward, based on these large studies, is that the risk of SM post RT is approximately 1 in 1,000 at 10 years. Giving RT has to be balanced against the risk of cancer recurrence if no RT is given.…”