Subsequent primary cancer incidence in cervical cancer survivors: insights from a comprehensive cohort study utilizing combined Japanese population-based cancer registries.

Objective: This study aimed to evaluate the incidence of subsequent primary cancer (SPC) among cervical cancer survivors in Japan.

Methods: Data from the cancer registries of Osaka, Kanagawa, and Miyagi prefectures were combined. The cohort included individuals diagnosed with invasive and in situ cervical cancer between 1980 and 2010, with the SPC incidence evaluated until 2015. The incidence and standardized incidence ratio (SIR) for different SPC sites were calculated. In addition, the association between SPC and radiotherapy was examined via competitive regression analysis.

Results: A total of 49,824 cervical cancer survivors were followed for up to 35 years, during which 4,507 (9.0%) of these survivors experienced SPC. Aside from the initial cancer, SPC was the most common cause of death among cervical cancer survivors. The most frequent SPC sites were the colorectal, breast, lung, and stomach, consistent with the frequency in the general population. A significant increase in the SIRs for bladder, lung, and colorectal cancers was observed (2.52, 1.63, and 1.44, respectively). Individuals who underwent radiotherapy had a higher risk of developing bladder cancer than those who did not, with a subdistribution hazard ratio of 2.28. The SIR for lung cancer significantly increased, particularly for the smoking-associated types, indicating the influence of smoking habits among survivors. Increased risk of specific SPCs was seen in both invasive and in situ cancer survivors.

Conclusion: Cervical cancer survivors should be informed about the risks of SPCs and educated on the prevention methods. Our study provides valuable insights into specific actions SPC prevention.