Rectosigmoid cancer after radiotherapy for prostate cancer can be detected early and successfully treated

Survival and peri-operative outcomes among patients with rectal cancer: the role of prior radiotherapy due to prostate cancer

PURPOSE

Patients with rectal cancer (RCa) and prior radiation for prostate cancer (PCa) are clinically complicated and may have worse outcomes than other RCa patients. This study investigates the impact of previous radiation for PCa on survival for patients with RCa.

METHOD

We conducted a population-based study identifying men who underwent surgical treatment of RCa from 2002 to 2010. Patients were classified into three cohorts: no prior PCa, prior PCa treated without radiotherapy, and prior PCa treated with radiotherapy. The primary outcome was overall survival. Secondary outcomes included RCa surgical approach, ICU admission, length of stay, ER visits, and delayed formation of a new stoma.

RESULTS

Seven thousand ninety-six men underwent surgery for RCa; 6867 patients had no prior PCa, 58 had prior PCa treated without radiotherapy, and 171 had prior PCa treated with radiotherapy. The 5-year overall survival was 62% (95% CI 61-64%) for patients without prior PCa, 46% (95% CI 25-65%) for patients with prior PCa treated without radiotherapy, and 42% (95% CI 29-54%) for patients with prior PCa treated with radiotherapy (p < 0.0001). In multivariable analysis, patients with prior PCa treated with radiotherapy were at increased risk of death (aHR 1.38, 95% CI 1.12-1.69) compared to those without prior PCa. Furthermore, patients with prior PCa treated with radiotherapy had a significantly increased risk of resection with permanent stoma.

CONCLUSIONS

Prior radiotherapy for PCa is a poor prognostic factor in RCa patients with significantly increased risk of death. Additionally, patients with prior radiotherapy for PCa are more likely to require a permanent stoma.

Secondary Cancers After Radiation Therapy for Primary Prostate or Rectal Cancer

Literature about the risk of secondary cancer after radiation therapy (RT) of prostate and rectal cancer reveals contradictory results. We conducted a meta-analysis to examine whether the RT induces secondary rectal or prostate cancer in patients, respectively, with prostate or rectal cancer. All studies published in Medline or Pubmed up to March 3, 2015, containing RT of primary rectal or prostate cancer, and providing risk estimates of secondary prostate or rectal cancer were considered as eligible. Relative risk (RR) and standardized incidence ratios (SIR) were calculated using the random-effects model. Twenty studies met the inclusion criteria. 12 of them were from the Surveillance, Epidemiology, and End Results (SEER) database. For prostate cancer patients, pooled adjusted RRs or SIRs did not show an effect on the risk of secondary rectal cancer. However, notwithstanding the limitations of SEER-based studies, the subgroup of prostate cancer patients receiving external beam radiation therapy (EBRT) showed an increased risk of rectal cancer. For rectal cancer patients, pooled adjusted RR of prostate cancer was 1.12 (95 % CI, 0.44-2.8) and SIR was 0.40 (95 % CI, 0.29-0.55). All studies included in the SIR analysis of rectal cancer were derived from the SEER data source. Based on current evidence, RT for prostate cancer patients had no effect on rectal cancer incidence, except for patients who received EBRT therapy. However, compared with the general population, RT for rectal cancer is associated with a decreased prostate cancer risk as found in SEER-based studies.

Radiation therapy for prostate cancer increases the risk of subsequent rectal cancer

PURPOSE

To assess whether radiation therapy for prostate cancer (PCa) increases the risk of metachronous rectal cancer (RCa) and compare outcomes of RCa after radiation therapy and surgery.

PATIENTS AND METHODS

The Israel Cancer Registry was queried to identify patients with PCa and RCa diagnosed between 1982 and 2005. The age adjusted standardized incidence ratio (SIR) of RCa was defined as the ratio between the observed and expected (calculated) RCa cases and compared among the following: overall Israeli male population, patients with PCa treated with radiation therapy, patients with PCa treated surgically. The medical records of men diagnosed with RCa were reviewed and clinical characteristics retrieved.

RESULTS

Of 29,593 men diagnosed with PCa, 2163 were treated with radiation therapy, 6762 were treated surgically and 20,068 patients were treated with either primary androgen deprivation therapy or offered watchful waiting. Of the entire study cohort, 194 (0.65%) patients were diagnosed with subsequent RCa. Compared to the overall male population and stratified by treatment modality, the risk of developing RCa after radiation therapy was significantly increased (SIR = 1.81, 95% CI 1.2-2.5), whereas it was not increased in those managed by surgery (SIR = 1.22, 95% CI 0.85-1.65). RCa after radiation therapy was diagnosed at a more advanced stage, translating into inferior disease specific survival.

CONCLUSIONS

Compared to men diagnosed with PCa managed by surgery, we observed an increased risk of RCa in patients treated with radiation therapy. Further studies are needed to validate these findings and assess whether routine colonoscopic surveillance is warranted after pelvic radiation.

Secondary cancer after radiotherapy for prostate cancer: should we be more aware of the risk?

OBJECTIVES

As the number of prostate cancer survivors is increasing, the long-term health of prostate cancer patients has become a significant health issue. Radiation is known to induce malignant transformation, and prostate cancer radiotherapy is suggested to induce secondary malignancies. This report reviews the available data regarding the risk of secondary cancer after radiation for prostate cancer.

METHODS

Epidemiological studies of the secondary cancer risk in patients with a history of prostate cancer radiation and the literature regarding radiation-induced carcinogenesis were reviewed.

RESULTS

Prostate cancer is not associated with an increased number of additional malignancies. The data suggests a modest increase in secondary cancers associated with radiation for prostate cancer, as approximately one in 70 patients undergoing radiation and surviving more than 10 yr will develop secondary cancer. The most common sites for secondary cancers are bladder and rectum. In addition to the cancers adjacent to the radiation field, there is also an increase of cancers in distant sites, such as lung. The increased risk for secondary cancers is reported after external radiation, not after brachytherapy. The available data originated from studies of patients undergoing conventional radiotherapy. New treatment methods, such as intensity-modulated radiotherapy, may be associated with a higher risk of secondary cancers.

CONCLUSION

Although the incidence of secondary cancers after prostate cancer radiotherapy is not dramatically different from the overall population, patients should be informed about this risk. Other treatment modalities should be considered for patients with long life expectancy and for patients with additional risk factors.