Clinical Briefs

By Louis Kuritzky, MD, Clinical Assistant Professor, University of Florida, Gainesville. Dr. Kuritzky is a consultant for GlaxoSmithKline and is on the speaker's bureau of GlaxoSmithKline, 3M, Wyeth-Ayerst, Pfizer, Novartis, Bristol-Myers Squibb, AstraZeneca, Jones Pharma, and Boehringer Ingelheim.

Ethnic and Racial Differences in the Smoking-Related Risk of Lung Cancer

Although cigarette smoking is the primary risk factor for lung cancer (LCA), with similar amounts of smoking exposure some groups demonstrate greater incidence of LCA than others. To gain insight into LCA susceptibility, an analysis of data from the Multiethnic Cohort Study stratified smokers (n = 183,813) by number of cigarettes smoked, gender, and ethnicity (African American, Japanese-American, Latino, Native Hawaiian, and Caucasian). Three tiers of smoking intensity were selected: 10 or less, 11-20, and 30 or greater cigarettes per day.

For the lowest tertile of smoking intensity, African Americans and Native Hawaiians had a three-fold greater risk of LCA than Japanese Americans or Latinos, and more than double the risk of Caucasians. At intermediate levels of smoking intensity, the African American/Hawaiian population risk was still more than double that of Latino/Japanese Americans. At the highest levels of smoking, risks were similar between all ethnicities, and were only modestly influenced by gender. Although the explanation for differences between LCA risk amongst different ethnicities is not fully clear, it is recognized that, for instance, Blacks have higher levels of cotinine (a primary nicotine metabolite) than others who smoke the same number of cigarettes, suggesting a difference in metabolism, greater environmental exposure, different smoking technique, or some combination of similar factors.

Haiman CA, et al. N Engl J Med. 2006;354:333-342.

Neuropathy Among the Diabetes Control and Complications Trial Cohort 8 Years After Trial Completion

Neuropathy is one of the 3 cardinal microvascular complications of diabetes that have been show to be favorably impacted by tight glucose control. At the conclusion of the Diabetes Control and Complications Trial (DCCT), neuropathy was reduced by approximately one-third in the tight control group vs conventional treatment. Study subjects from both treatment arms were encouraged to participate in tight control from that point onward, since better control was associated with numerous favorable outcomes.

Eight years after DCCT completion 1,257 of the original 1,441 participants were re-examined for neuropathy. Neuropathy was assessed by symptoms alone or by the Michigan Neuropathy Screening Instrument (MNSI). Even though the overall level of glycemic control amongst the 2 groups was quite similar over the 8 year hiatus since DCCT conclusion, there remained a statistically significant lesser prevalence of neuropathy in the group originally assigned to tight control. Overall, the prevalence of neuropathy according to the MNSI was 64% less in the prior tight control group. Lower extremity amputations were similar in both groups.

These data support the concept that early intensive treatment of diabetes may have long-lasting impact. Eight years after participation in a 6.5 year (mean) intensive treatment trial, subjects achieving lower levels of A1c continue to enjoy lesser prevalence of neuropathy.

Martin CL, et al. Diabetes Care. 2006;29:340-344.

Saw Palmetto for Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is the most common neoplastic condition in aging men. Alpha blockers (ABL) such as alfuzosin, doxazosin, tamsulosin, and terazosin provide substantial symptomatic relief, but are not disease-modifying (ie, they do not alter outcomes such as need for surgical intervention or acute urinary retention). Alpha reductase inhibitors such as dutasteride and finasteride are disease modifying, but do not provide prompt symptomatic relief. Many men and their clinicians look to alternative therapies such as saw palmetto (SAW) for treatment, rather than rely upon the above traditional methods. Small studies, some with design flaws, have suggested beneficial effects for men with BPH using SAW. The study by Bent follows rigorous methodology to clarify the effectiveness of SAW for both subjective (eg, quality of life) and objective (eg, prostate size, urinary flow rate, PSA) parameters.

Men older than age 49 (n = 225) with moderate-to-severe BPH were randomly assigned to SAW (160 mg b.i.d.) or placebo and followed for 1 year. To 'cut to the chase,' SAW was not superior to placebo for any measured end point. The evidence-based role of SAW for treatment of BPH is tenuous.

Bent S, et al. N Engl J Med. 2006;354:557-566.