APPENDIX V: IMPACT AND EFFECTIVENESS OF

Ruth Rosenblatt, MD

A. Breast Cancer/Mammography

The National Cancer Institute (NCI) has recently reported a 5% decline in breast cancer mortality in the years 1989 to 1993. This trend in mortality reduction, despite a gradual increase in the incidence of breast cancer, is attributed to improved treatment modalities and to the detection of smaller, more favorable tumors. The NCI's Surveillance, Epidemiology and End Result (SEER) data from 1973-1992 show a decrease in breast tumor size at diagnosis. Screening mammography among women at average risk aged 50-74 has been shown to reduce breast cancer mortality by 30-40%.¹ The current decline in breast cancer mortality is also thought to be related to more aggressive use of mammography.

An important development in the past decade has been the steady emphasis on improving the quality of mammography. This has been accomplished first through the voluntary accreditation programs initiated by the American College of Radiology in 1987. Subsequently, in 1992, the Mammography Quality Standards Act (MQSA) has established obligatory accreditation for any facility performing mammography, thereby achieving some uniformity and reproducibility, and ensuring a level of diagnostic quality as well as acceptable exposure dose. The final version of MQSA was passed in October of 1997.

There have been recent assessments of mammography from the point of view of risks vs benefits of radiation exposure. An analysis of the current literature regarding the benefits of cancer detection and the risk of carcinogenesis concludes that "if a woman begins annual screening at age 35 and continues until age 75, the benefit of reduced mortality is projected to exceed the radiation risk by a factor of more than 25".²

An ancillary question raised by some investigators is whether high-risk women, including those with BRCA mutations, are at higher risk for radiation-induced breast cancer.³ This is particularly a concern because screening of individuals who test positive for genetic breast cancer predisposition may begin at an age younger than 35. In this age group, mammographically dense breast tissue may render the mammogram less reliable as a screening tool. These concerns may serve as an impetus to develop additional imaging modalities such as ultrasound and MRI, currently investigational for breast cancer screening. Information regarding the efficacy of MRI and ultrasound as screening tools is still to be reviewed.

B. Ovarian Cancer/Pelvic Ultrasound

Early detection of ovarian malignancy offers the most effective means of reducing the current high mortality rate. Ultrasound screening of postmenopausal women for ovarian carcinoma has not developed into a successful nor cost-effective undertaking, even though the ultrasound examination is a more sensitive tool than the physical examination in evaluating ovarian volume. This is largely due to the low prevalence of ovarian malignancy in the general population. However, acceptable cost effectiveness may be achieved in a genetically high-risk population in which a multimodality approach is used that combines tumor markers (ie. CA125) with pelvic ultrasound, including color flow Doppler analysis. Ultrasound can display certain morphologic features of ovarian malignancy such as thick septae and papillations with fluid spaces. In addition, blood flow pattern of low impedance has been described as a typical feature of ovarian malignacy.⁵

References:

1. Kerlikowske et al. Efficacy of screening mammography. JAMA, 173:149-154, (1995).

2. Mettler FA et al. Benefits versus risks from mammography. Cancer, 77:903-909, (1996).

3. Otter WD et al. Exclusion from mammographic screening of women genetically predisposed to breast cancer will probably eliminate mammographically induced breast cancer. Anticancer Research, 13:1113-1116, (1993).

4. Taylor KJW, Schwartz PE. Screening for early ovarian cancer. Radiology, 192:1-10, (1994).

5. Jacobs I et al. Prevalence screening for ovarian cancer in postmenopausal women by CA125 measurement and ultrasonography. BMJ, 306:1030-1034, (1993).