Association between smoking, bladder cancer may be increasing

The risk for bladder cancer among current smokers in New Hampshire may have nearly doubled since the mid-1990s, according to results of a case-control study.

The results of the study also indicated that smoking fewer cigarettes over an extended time period may be more harmful than smoking more cigarettes in a shorter span.

The study included data from 1,170 patients with urothelial carcinoma and 1,413 control patients. The researchers examined bladder cancer risk in relation to smoking practices based on data from a large, population-based, case-control study conducted in Maine, New Hampshire and Vermont from 2001 to 2004. These results were then compared with two case-control studies conducted in New Hampshire from 1994 to 1998 and from 1998 to 2001 to determine the changes in smoking-induced bladder cancer risk over time.

Compared with never smokers, the OR for bladder cancer risk was increased among regular smokers (OR=3.0; 95% CI, 2.4-3.6) and current smokers (OR=5.2; 95% CI, 4.0-6.6).

A statistically significant increasing trend in bladder cancer risk associated with smoking was observed in New Hampshire during the three time intervals: 1994-1998, 1998-2001 and 2002-2004. Among former smokers, the OR for bladder cancer risk increased from 1.4 from 1994-1998 to 2.0 from 1998-2001 to 2.6 from 2002-2004. Among current smokers, the OR increase was from 2.9 (95% CI, 2.0-4.2) to 4.2 (95% CI, 2.8-6.3) to 5.5 (95% CI, 3.5-8.9).

An accompanying editorial was written by Anthony J. Alberg, PhD, MPH, of the Hollings Cancer Center and division of biostatistics and epidemiology in the department of medicine at the Medical University of South Carolina and James R. Hebert, MSPH, ScD, of the Cancer Prevention and Control Program and department of epidemiology and biostatistics at the Arnold School of Public Health at the University of South Carolina.

“The most noteworthy finding [of this study] was that the association between smoking and bladder cancer increased substantially from 1994 to 2004,” they wrote.

Changing carcinogenic properties of cigarettes may be the root of the increase in bladder cancer risk, according to Alberg and Hebert.

“An important element of this research will be to more precisely pinpoint the specific role of cigarette additives,” they wrote. “This study highlights the need for continued vigilance in monitoring the impact of changing cigarette content and design on disease risk.”

Baris D. J Natl Cancer Inst. 2009;101:1553-1561.