Patients with cancer detected on screening mammography undergo less toxic treatment

Women who have their breast cancers detected by physical examinations are at least twice as likely to undergo toxic treatments than those who have their cancer detected by mammography—regardless of the age of the woman, a new study shows.

The study reviewed 992 women with invasive breast cancer—460 of them had their cancer detected on screening mammography and 532 on physical examination, said the lead author of the study, Richard J. Barth, Jr., MD, Chief of the Division of Surgical Oncology at Dartmouth-Hitchcock Medical Center.

Overall, patients whose cancer was detected at physical examination were three times more likely to be treated with chemotherapy than those who had their cancer detected by screening mammography, said Dr. Barth. Women in the 40-49 age group were about two times more likely and women in the 70 and older age group were about five times more likely to undergo chemotherapy if their cancer was detected by physical examination, Dr. Barth said.

Chemotherapy is commonly recommended for patients with tumors larger than 1 cm in diameter or with cancer that has spread into the lymph nodes, he said. Cancers detected by mammography were half as large as those detected by physical exam. In addition, only 16% of those patients whose tumors were detected by mammography had cancer spread to the lymph nodes compared with 42% of those who had their breast cancer detected on physical examination, he said.

Overall, patients who had their breast cancer detected on physical examination were more than twice as likely to be treated with mastectomy rather than breast conservation, Dr. Barth added. Women in the 70 and older age group were about five times more likely to have a mastectomy if their cancer was detected by physical examination rather than mammography. Women in the younger age group were also more likely to have a mastectomy if they had their cancer detected by physical examination, Dr. Barth said.

While there continues to be debate on whether screening mammography increases survival of women ages 40-49 and 70 and older, there is no doubt that mammography detects cancer earlier, Dr. Barth said. This study emphasizes that screening mammography allows patients who are unfortunate enough to develop breast cancer to be treated with less-toxic therapy, regardless of their age. It provides strong supporting evidence that women over 40 should be screened with mammography, he said.

The study appears in the January 2005 issue of the American Journal of Roentgenology.