U.S. study shows no breast cancer/abortion link

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - Abortions and miscarriages do not raise the risk of breast cancer, despite claims by some groups and some studies that suggest they do, researchers said on Monday.

A study of more than 100,000 U.S. nurses found that those who had an abortion or miscarriage were no more likely to have breast cancer than any other woman in the study.

The findings fit with a 2003 report from an international expert panel put together by the U.S. National Cancer Institute.

"If you look at the high-quality evidence, it does not support an association between induced abortions and breast cancer," said Karin Michels of Brigham and Women's Hospital and Harvard Medical School in Boston.

But her team set out to create the most reliable type of research that is possible -- a prospective study, starting with women before they ever had cancer, and following them for years.

Her team's study, published in the Archives of Internal Medicine, began with 105,000 women aged 29 to 46 years in 1993. All were cancer-free to start with and filled out a detailed, anonymous questionnaire that included questions about abortions and miscarriages.

Previous studies have started with women who already had breast cancer and asked them whether they had ever had an abortion.

Michels said women with cancer who have had an abortion are much more likely to report this. "They are still soul-searching and looking for reasons," Michels said in a telephone interview.