Oral contraceptive use, parity, and constitutional characteristics in soft tissue sarcoma: a Swedish population-based case\u2013control study 1988\u20132009

Purpose The study was designed to investigate the influence of surrogate factors associated with sex (SH) and growth hormones (GH) on the risk of developing soft tissue sarcomas (STS). Background and methods The etiology of soft tissue sarcoma is largely unknown. We have studied the effect of hormone related factors on STS in the Swedish population between 1988 and 2009 using a population-based matched case‐control design. Results Our study is the largest on this topic to date, including 634 cases in a primary matched analysis and 855 cases in an unmatched sensitivity analysis. We identified protective effects connected to constitutional characteristics, hormonal and reproductive factors. Being shorter than your peers at age 11 was associated with an odds ratio (OR) of 0.51 (0.36‐0.74). Having used oral contraceptives (OC), OR 0.75 (0.49‐1.15), and high parity, OR 0.16 (0.04‐0.63), comparing three or more children to two or less, also appeared to reduce the risk of STS. The risk was further reduced with the duration of OC use (p = 0.01), comparing use for 11 years or more to use for 3 years or less yielded an OR of 0.10 (0.02‐0.41). No effect was observed for ever having had perimenopausal hormone therapy OR 1.02 (0.70‐1.47). The effect of BMI varied significantly with subtype (p = 0.03) and tumor location (p \ 0.001). Conclusions We observed surrogates of SH, GH, and insulin-like growth factor 1 to be associated with STS development. These findings are important as they may connect STSs to the group of hormone-dependent tumors, potentially revealing common treatment and prevention targets.