Might chronic inflammation be a factor in the development of breast cancer? That is one explanation for an association between long tem use of antibiotics and breast cancer reported in JAMA (2004;291: 827-35). A link was found between breast cancer and several different categories of antibiotics, suggesting that treatment for chronic or repeated infections might be the trigger for the cancer. That hypothesis is reinforced by the known anticancer effect of non-steroidal anti-inflammatory drugs.

A huge study in the Netherlands of 2412 non-smokers, 2794 former smokers, and 1508 current smokers looked at angiotensin converting enzyme incidence and deletion polymorphism and blood pressure (Journal of Hypertension 2004;22: 313-9). The deletion allele was associated with a raised systolic blood pressure and an increased risk of hypertension in smokers. These findings suggest a direct effect on blood pressure of smoking and carrying the deletion allele—a convincing demonstration of the interaction of genetic and environmental factors.

Hospital hot water systems may be contaminated by organisms of the Mycobacterium avium complex, and some patients (especially those with HIV infection) may develop clinical signs of infection—but others may not. A study in one hospital in the United States (Journal of Infectious Diseases 2004;189: 98-104) found that 35 of 131 patients with positive sputum had Mycobacterium avium complex disease, …