Rapiti Elisabetta, Fioretta Gerald, Verkooijen Helena M, Zanetti Roberto, Schmidlin Franz, Shubert Hyma, Merglen Arnaud, Miralbell Raymond, Bouchardy Christine
Geneva Cancer Registry, Institute for Social and Preventive Medicine, University of Geneva, Geneva, Switzerland.
Int J Cancer. 2008 Sep 1;123(5):1141-5. doi: 10.1002/ijc.23601.
Radiotherapy can induce second cancers. Controversies still exist regarding the risk of second malignancies after irradiation for prostate cancer. We evaluated the risk of developing colon and rectum cancers after prostate cancer in irradiated and nonirradiated patients. Using data from the population-based Geneva cancer registry, we included in the study all men with prostate cancer diagnosed between 1980 and 1998 who survived at least 5 years after diagnosis. Of the 1,134 patients, 264 were treated with external radiotherapy. Patients were followed for occurrence of colorectal cancer up to 31 December, 2003. We calculated standardized incidence ratios (SIR) using incidence rates for the general population to obtain the expected cancer incidence. The cohort yielded to 3,798 person-years. At the end of follow-up 19 patients had developed a colorectal cancer. Among irradiated patients the SIR for colorectal cancer was 3.4 (95% confidence intervals [CI] 1.7-6.0). Compared to the general population, the risk was significantly higher for colon cancer (SIR = 4.0, 95% CI: 1.8-7.6), but not for rectal cancer (SIR = 2.0, 95% CI: 0.2-7.2). The risk of colon cancer was increased in the period of 5-9 years after diagnosis (SIR = 4.7, 95% CI: 2.0-9.2). The overall SIR of secondary cancer in patients treated with radiotherapy was 1.35 (p = 0.056). Nonirradiated patients did not have any increased risk of rectal or colon cancer. This study shows a significant increase of colon but not rectum cancer after radiotherapy for prostate cancer. The risk of second cancer after irradiation, although probably small, needs nevertheless to be carefully monitored.
放射治疗可诱发二次癌症。关于前列腺癌放疗后发生二次恶性肿瘤的风险，目前仍存在争议。我们评估了接受放疗和未接受放疗的前列腺癌患者发生结肠癌和直肠癌的风险。利用基于人群的日内瓦癌症登记处的数据，我们纳入了1980年至1998年间确诊为前列腺癌且诊断后至少存活5年的所有男性。在1134例患者中，264例接受了外照射放疗。对患者随访至2003年12月31日，观察结直肠癌的发生情况。我们使用一般人群的发病率计算标准化发病率（SIR），以获得预期的癌症发病率。该队列的人年数为3798人年。随访结束时，有19例患者发生了结直肠癌。在接受放疗的患者中，结直肠癌的SIR为3.4（95%置信区间[CI]1.7 - 6.0）。与一般人群相比，结肠癌的风险显著更高（SIR = 4.0，95% CI：1.8 - 7.6），但直肠癌的风险未显著升高（SIR = 2.0，95% CI：0.2 - 7.2）。诊断后5 - 9年期间结肠癌风险增加（SIR = 4.7，95% CI：2.0 - 9.2）。接受放疗患者的二次癌症总体SIR为1.35（p = 0.056）。未接受放疗的患者患直肠癌或结肠癌的风险没有增加。这项研究表明，前列腺癌放疗后结肠癌风险显著增加，而直肠癌风险未增加。放疗后二次癌症的风险尽管可能较小，但仍需仔细监测。
