In the setting of breast cancer, breast-conserving surgery was a predictor for radiotherapy-associated thoracic soft tissue sarcomas, according to results of a study published in The Lancet Oncology.

Soft tissue sarcomas are a rare side-effect of radiotherapy, but prevalence in the US is increasing. Despite this trend, few studies have focused on identifying risk factors. Therefore, researchers sought to evaluate potential predictors of sarcoma risk.

Data were sourced from the Kaiser Permanente (KP) breast cancer survivors cohort, collected from between January 1990 and December 2016, and the US Surveillance, Epidemiology, and End Results (SEER) 13 cancer registries, collected from between January 1992 and December 2016.

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The KP (n=15,940) and SEER (n=457,300) cohorts comprised women median ages 61 and 59 years at diagnosis, 91.4% and 79.6% were White, and 58.4% and 52.7% had stage I disease, respectively.

In the KP cohort, 19 patients developed thoracic soft tissue sarcomas. Risk was associated with initial radiotherapy (P =.0052). Eleven patients developed angiosarcoma, and risk was associated with breast-conserving surgery compared with mastectomy (P =.018), hypertension (P =.017), and diabetes (P =.036). Eight patients developed other sarcomas; risk was associated with alkylating agents (P =.026).

In the SEER cohort, risk for soft tissue sarcomas associated with increased time since breast cancer diagnosis, increased age, stage II disease, initial radiotherapy, and breast-conserving surgery compared with mastectomy (all P <.0001).

Of 430 patients in the SEER cohort with sarcomas, 268 were angiosarcoma and 162 were other sarcomas. Risk for angiosarcoma was associated with the same risk factors as sarcomas overall (all P ≤.017) plus radiotherapy with breast-conserving surgery compared with mastectomy (P =.012) and initial chemotherapy (P =.047). Risk for other sarcomas was associated with stage II breast cancer (P =.0026), Black compared with White race (P =.015), and initial radiotherapy (P =.015).

These study findings showed risk for thoracic soft tissue sarcoma was higher for those who underwent breast-conserving surgery, received radiotherapy, anthracyclines, and had a history of hypertension and/or diabetes prior to breast cancer diagnosis.


Veiga LHS, Vo JB, Curtis RE, et al. Treatment-related thoracic soft tissue sarcomas in US breast cancer survivors: a retrospective cohort study. Lancet Oncol. 2022;23(11):1451-1464. doi:10.1016/S1470-2045(22)00561-7