Breast cancer accounts for greater than 200,000 new cases each year, and results in approximately 40,000 deaths per year. Prostate cancer is the most common cancer in males and remains the second most common cause of cancer-related deaths in men, with approximately 230,000 cases and 28,900 deaths yearly.
Breast Cancer Screening
Breast cancer accounts for greater than 200,000 new cases each year, and results in approximately 40,000 deaths per year. The average lifetime risk for breast cancer is approximately 8%.
Three different modalities are commonly employed for screening average risk women for breast cancer:
- Self-breast examination: Although a monthly self-breast examination has been recommended for all women older than age 20 years, there has been no randomized trial showing a mortality benefit. However, a large proportion of cancers are usually first identified by the patient, hence, most authorities recommend counseling women on proper self-breast examination.
- Clinical breast examination: Both the USPSTF and ACS recommend a regular clinical breast examination, but the frequency and demographics (age range) differ. Randomized trials have shown some benefit of a high-quality clinical breast examination, and the mortality benefit of screening mammography is enhanced by 5% to 20% when combined with clinical breast examinations.
- Mammography: Based on a large number of randomized trials and subsequent meta-analysis, regular screening mammography has been shown to decrease breast cancer mortality. It is estimated that in women between 40 and 70 years, regular screening mammography offers a 15% relative risk reduction in breast cancer mortality.
The age at which breast cancer screening should start has been the subject of considerable debate. The current consensus opinion of the ACS and the NCI is to begin yearly mammography for all women older than 40 years of age. Thus, a comprehensive breast cancer screening strategy would include regular self-breast examinations every month, a clinical breast examination yearly, and an annual mammogram starting at age 40 years.
Magnetic resonance imaging (MRI) of the breast appears to be particularly useful in younger women as well as in women with dense breast tissue, in whom mammography is less sensitive. This technique has not yet been formally evaluated in a screening scenario, and thus cannot be recommended routinely to all patients.
Genetic testing for BRCA1 and 2 mutations is reserved for patients with a high-risk family history, which includes two or more first-degree relatives with breast or ovarian cancer. These mutations have incomplete penetrance; hence referral for genetic counseling for a full discussion of prevention options, including chemo-prevention, is useful.
Cervical Cancer Screening
Although its incidence in the United States has been steadily decreasing, cervical cancer is the second most common cancer worldwide. The Papanicolaou (Pap) cytology test represents one of the triumphs of oncologic screening with an estimated 70% decline in cervical cancer related mortality.
Interestingly, there have never been any randomized trials done to establish efficacy, but numerous population and cohort studies have confirmed the extraordinary mortality reduction of regular Pap screening.
Screening appears to be effective when started within 3 years of intercourse, or at age 21 years. Pap screening should be continued yearly, until age 30 when women who have had three or more consecutive normal tests may be tested every 2 to 3 years.
High-risk individuals, which include those with a history of sexually transmitted disease, multiple sexual partners, or those with a history of an abnormal Pap, should continue yearly testing.
Women who have had a hysterectomy and cervix removal for a benign illness do not appear to benefit from continued yearly screening. Similarly, women older than the age of 70 years, with a normal Pap in the last 10 years, also may choose to stop screening.
The etiologic agent associated with virtually all cervical cancers is the human papillomavirus (HPV). The use of reflex HPV DNA testing in patients who demonstrate atypical squamous cells of undetermined significance on Pap cytology appears to enhance the sensitivity of cytological testing in identifying both invasive cervical cancer as well as carcinoma in situ.
A wide array of assays are available for cytological testing: Liquid based cytology and DNA testing appear to be superior to conventional cytology, but definitive data are lacking, and the choice should be based on local expertise and availability.
The recent introduction of a quadrivalent HPV vaccine marks a new step in the prevention of cervical cancer. This appears to be effective in preventing up to 80% of HPV infections and subsequent cervical neoplasia and is now recommended for girls aged 13 years and older. However, this vaccination has not yet eliminated the requirement for regular Pap cytological examinations.