The study of 61,688 women 40 years and older (574 with invasive breast cancer) who participated in a breast cancer screening program at Group Health Cooperative in Seattle, WA, found that mammography plus clinical breast examination detected 470 (82%) of the cancers; mammography detected 445 (78%) of the breast cancers and clinical breast examination detected 121 (21%) of the cancers. ???Adding clinical breast examination to screening mammography detected an additional 25 (4%) cancers in the study population,??? said Nina Oestreicher, PhD, scientist at Kaiser Permanente Division of Research in Oakland, CA. ???Given this modest benefit and the current lack of evidence of mortality reduction for early detection of cancers by clinical breast examination alone, it is unlikely that the addition of clinical breast examination to a mammography screening program will result in substantial mortality benefits,??? she added.

Women with dense breasts experienced the most benefit, but also the most harm from including clinical breast examination in a mammography screening program. They were more than twice as likely to have their cancer detected by clinical breast examination alone, but they were also nearly twice as likely to be told that they might have breast cancer when they really didn??™t (false positive report), Dr. Oestreicher said. These false positive reports lead to more biopsies, she said.

The study emphasizes that mammography far outperforms clinical breast examination regardless of a patient??™s age and breast density, said Dr. Oestreicher. Some breast cancer screening programs are considering whether they should include clinical breast examination. This study provides insight as to the ???benefits??? and ???harms??? of clinical breast examination, she said. ???It is up to a woman and her physician to weigh the tradeoffs of clinical breast examination, depending on her breast density, breast cancer risk and personal preferences,??? Dr. Oestreicher added.

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

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Reproductive-related cancers accounted for nearly half of all cancer in women and nearly a third of all cancer in men. For women, a strong association was found between breast cancer in women under age 50 and larger birth size. Women in the highest category of birth weight (4kg or greater) were four times as likely to get breast cancer before age 50, compared with women in the lowest category (less than 3 kg). On the other hand, women who were large at birth were only half as likely to get endometrial cancer compared to their smallest counterparts. For men, the most common reproductive-related cancer, of the prostate gland, was analyzed but no association to birth factors was found.

While the researchers note that some of their findings may have arisen by chance, it is plausible that the associations between birth weight and adult cancer are related to some aspects of the fetal environment or the number of cells at risk of carcinogenesis.

"We have found some evidence supporting the hypothesis that larger birth size is associated with increased risk of certain adult cancers," the authors report. "However, our findings suggest that positive associations were not uniform across all cancer sites, but were particular to just a few sites. Furthermore, our findings generate the hypothesis, which merits further study, that rates of endometrial cancer are lower in women who had higher birth rates."

Since previous studies have found associations between smaller birth size and increased risks of adult heart disease and diabetes, the authors conclude, "Both circulatory disease and cancer need to be considered in determining the net effect of prenatal influences on adult morbidity and mortality."

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