Clinical characteristics and survival patterns of subsequent sarcoma, breast cancer, and melanoma after childhood cancer in the DCOG-LATER cohort.

PURPOSE

Childhood cancer survivors are at increased risk of developing subsequent malignant neoplasms (SMNs). We compared survival and clinical characteristics of survivors with SMNs (sarcoma, breast cancer, or melanoma) and a population-based sample of similar first malignant neoplasm (FMN) patients.

METHODS

We assembled three case series of solid SMNs observed in a cohort of 5-year Dutch childhood cancer survivors diagnosed 1963-2001 and followed until 2014: sarcoma (n = 45), female breast cancer (n = 41), and melanoma (n = 17). Each SMN patient was sex-, age-, and calendar year-matched to 10 FMN patients in the population-based Netherlands Cancer Registry. We compared clinical and histopathological characteristics by Fisher's exact tests and survival by multivariable Cox regression and competing risk regression analyses.

RESULTS

Among sarcoma-SMN patients, overall survival [hazard ratio (HR) 1.88, 95% confidence interval (CI) 1.23-2.87] and sarcoma-specific mortality (HR 1.91, 95% CI 1.16-3.13) were significantly worse compared to sarcoma-FMN patients (foremost for soft-tissue sarcoma), with 15-year survival rates of 30.8% and 61.6%, respectively. Overall survival did not significantly differ for breast-SMN versus breast-FMN patients (HR 1.14, 95% CI 0.54-2.37), nor for melanoma-SMN versus melanoma-FMN patients (HR 0.71, 95% CI 0.10-5.00). No significant differences in tumor characteristics were observed between breast-SMN and breast-FMN patients. Breast-SMN patients were treated more often with mastectomy without radiotherapy/chemotherapy compared to breast-FMN patients (17.1% vs. 5.6%).

CONCLUSIONS

Survival of sarcoma-SMN patients is worse than sarcoma-FMN patients. Although survival and tumor characteristics appear similar for breast-SMN and breast-FMN patients, treatment differs; breast-SMN patients less often receive breast-conserving therapy. Larger studies are necessary to substantiate these exploratory findings.