The population of cancer patients with second primary malignancies (SPMs) is rapidly growing. The relationship between radiotherapy and SPMs for some types of tumors is unknown or debated. In this study, we identify 24 types of first primary malignancies (FPMs) between 2004 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) database. Patients in the radiotherapy group were matched to those in the no radiotherapy group with a matching ratio of 1:1. After propensity-score matching (PSM), additional competing risk regression analyses were performed to calculate the efficacy of radiotherapy to SPMs in the PSM-adjusted population. In addition, the Fine and Gray model was utilized in the primary cohorts, and stratified analyses were performed based on surgery. This study includes a total of 2,831,789 eligible patients with tumors diagnosed from 2004 to 2015 in the SEER 18 database, amongst whom 100,194 (3.5%) patients developed SPMs. We observe higher risks of SPMs associated with radiotherapy in several types of tumors in the PSM-adjusted populations (small bowel adenocarcinoma, small cell lung carcinoma, prostate adenocarcinoma, urinary bladder transitional cell carcinoma, invasive ductal breast carcinoma, invasive lobular breast carcinoma, and Hodgkin lymphoma). The results in the PSM-adjusted populations were consistent with outcomes in the multivariable competing risk models. Meanwhile, in subgroup analyses stratified by surgery, some other types of tumor (except for those with positive results in the PSM-adjusted cohorts) with radiotherapy were also associated with a higher prevalence of SPMs in the subgroups of surgical treatment (pancreatic adenocarcinoma, rectal adenocarcinoma, lung adenocarcinoma and follicular thyroid carcinoma in the surgery subgroups). The impact of radiotherapy on the incidence of secondary malignancies is distinct in different types of cancer. These findings merit further investigation and may ultimately impact treatment decision-making for tumor management.

中文翻译：

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放疗对继发性恶性肿瘤发病率的影响：美国 SEER 癌症登记处的一项泛癌研究

患有第二原发恶性肿瘤 (SPM) 的癌症患者人数正在迅速增长。对于某些类型的肿瘤，放疗和 SPM 之间的关系是未知的或有争议的。在这项研究中，我们在监测、流行病学和最终结果 (SEER) 数据库中确定了 2004 年至 2015 年间的 24 种类型的原发性恶性肿瘤 (FPM)。放疗组患者与未放疗组患者匹配比例为1:1。在倾向评分匹配 (PSM) 之后，进行了额外的竞争风险回归分析，以计算 PSM 调整人群中放疗对 SPM 的疗效。此外，在主要队列中使用 Fine 和 Gray 模型，并根据手术进行分层分析。本研究共包括 2,831，SEER 18 数据库中 2004 年至 2015 年诊断出的 789 名符合条件的肿瘤患者，其中 100,194 名（3.5%）患者发生了 SPM。我们观察到，在 PSM 调整人群（小肠腺癌、小细胞肺癌、前列腺腺癌、膀胱移行细胞癌、浸润性导管乳腺癌、浸润性小叶乳腺癌和霍奇金淋巴瘤）。PSM 调整人群中的结果与多变量竞争风险模型中的结果一致。同时，在按手术分层的亚组分析中，一些其他类型的肿瘤（除了那些在 PSM 调整队列中获得阳性结果的肿瘤）也与手术治疗亚组（胰腺腺癌、直肠腺癌、肺腺癌和滤泡性甲状腺癌）中 SPM 的较高患病率相关。手术亚组）。放疗对继发性恶性肿瘤发病率的影响在不同类型的癌症中是不同的。这些发现值得进一步研究，并可能最终影响肿瘤管理的治疗决策。