Highlights of This Issue

Lymphoid malignancies occur at lower rates in Asians than other racial/ethnic groups in the United States. To explore this further, Clarke and colleagues examined incidence patterns of lymphoid malignancies among populations characterized by ethnicity, birthplace, residential neighborhood socioeconomic status, and ethnic enclave status. The authors used data from the California Cancer Registry and the U.S. Census. They found that incidence rates of follicular lymphoma (FL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and nodular sclerosis Hodgkin lymphoma (NS HL) were significantly lower among foreign-born than U.S.-born Asians. These observations support strong roles of environmental factors in the causation of FL, CLL/SLL, and NS HL.

Few studies have evaluated the impact of following recommended lifestyle behaviors on cancer, cardiovascular disease and all-cause mortality. McCullough and colleagues evaluated diet and lifestyle questionnaires from over 111,000 nonsmoking men and women from the Cancer Prevention Study (CPS)-II Nutrition Cohort and assessed subjects′ adherence to cancer prevention guidelines of the American Cancer Society. They report that the relative risk of all-cause mortality was lower for participants with high guideline adherence versus low. Similar inverse associations were found with cardiovascular disease and cancer mortality. This large study indicates that following cancer prevention guidelines for diet, exercise and alcohol consumption may substantially lower risk of premature mortality in older adults.

It is hypothesized that exercise can lead to a decrease in breast cancer risk through several hormonal and nonhormonal mechanisms. Smith and colleagues used data from the Women in Steady Exercise Research (WISER) study to investigate the effects of aerobic exercise on premenopausal sex hormone levels. They report that while exercisers experienced significant increases in aerobic fitness, lean body mass, and decreases in percent body fat, there were no significant changes in sex hormone levels. These studies indicate that any favorable effects that moderate aerobic exercise may have on breast cancer risk are unlikely to be the consequence of changes in sex hormone levels.

TGF-β acts as a suppressor of tumor initiation but can also promote later malignant stages. Scollen and colleagues evaluated 354 SNPs in seventeen TGF-β signaling pathway genes for their association with invasive breast cancer risk. Three SNPs were found to be associated with invasive breast cancer risk. Tumor subtype analysis revealed that one of the SNPs may be associated with increased risk of developing progesterone receptor negative (PR⁻) tumors. This large study agrees with previous reports and indicates that it is unlikely that other common variants in the TGF-β signaling pathway contribute significantly to breast cancer risk.