Breast Neoplasms in Women Treated With X-Rays for Acute Postpartum Mastitis 2

TLDR

The study used a mail‑survey cohort of 571 women treated with X‑ray therapy for acute postpartum mastitis, comparing their breast cancer incidence over 34 years to three nonirradiated control groups (sisters, untreated mastitis patients, and their sisters). Women received a mean dose of 247 rads and had a relative risk of 2.2 for years 10–34 and 3.6 for years 20–34, with a linear dose–response, fractionation not reducing risk, age at exposure not altering excess risk, and an overall excess incidence of about 8–10 cases per million women per rad per year (~0.5 % per rad).

Abstract

Breast cancer has been studied by mail survey up to 34 years in 571 of 606 women treated with X-rays for acute postpartum mastitis. The incidence of neoplasms was compared with that of three nonirradiated control groups—nonirradiated sisters of the treated women, women with acute postpartum mastitis not treated with X-rays, and their nonirradiated sisters. For the irradiated group, with a mean dose of 247 rads to both breasts, the overall relative risk of breast cancer was 2.2 for years 10–34 post irradiation and 3.6 for years 20–34. The dose response for malignant and benign breast neoplasms was compatible with a linear fit. For comparable total doses, fractionation of exposure did not reduce carcinogenic action. Women over age 30 years at radiation treatment had as great an excess risk of breast cancer as did younger women. The overall excess risk of developing breast cancer was about 8–10 cases per million women per rad per year, an increase of about 0.5% per rad.