Breast cancer radiation therapy linked with oesophageal cancer risk

Adjuvant radiation after mastectomy for primary breast cancer is associated with a moderately increased risk of squamous cell esophageal cancer, but not adenocarcinoma, suggest results of a retrospective, population-based study of roughly 244,000 women.

The estimated relative risk of squamous cell esophageal cancer 5 to 9 years and 10 years or more after postmastectomy radiotherapy is 2.83 and 2.17, respectively, investigators report in the February 15th issue of the American Journal of Epidemiology.However, the incidence of esophageal cancer in the cohort was still low (9.65 per 100,000 person-years of observation).Commenting on his team's findings, Dr. Alfred I. Neugut from Columbia University in New York said: "I think for practicing doctors, the interesting point is that, while there is an increased risk of esophageal cancer following breast cancer radiotherapy, it is not very large and should not affect the use of this type of therapy, though they may want to discourage these women from smoking."The current findings confirm earlier findings by the same investigators that radiation-induced squamous cell esophageal cancer can arise after a substantial latency period (see Reuters Health report January 16, 1998.)The increase in esophageal cancer risk after postmastectomy adjuvant radiation was primarily due to tumors in the upper and middle thirds of the esophagus, closest to the site of irradiation, the researchers note.As expected, there was no increase in risk of any type of esophageal cancer with postlumpectomy radiation, which entails lower radiation exposure.The finding that radiotherapy after mastectomy does not raise the risk of adenocarcinoma "reflects the fact that adenocarcinomas of the esophagus occur solely in the lowest third and the radiotherapy port for breast cancer does not affect that area of the esophagus," Dr. Neugut told Reuters Health.(Source: Am J Epidemiol 2005;161:330-337: Reuters Health: Megan Rauscher: Oncolink: February 2005.)