VANCOUVER, BRITISH COLUMBIA (EGMN) – Small cell lung cancer presentation varies by sex and race, according to a retrospective analysis of U.S. national data spanning a 32-year period.

Women were more likely than men to have limited disease at diagnosis and had better survival, Dr. Shagun Arora reported at the annual meeting of the American College of Chest Physicians. African Americans were younger than whites at diagnosis, and the small cell type made up a smaller proportion of all lung cancers in African American patients than in white patients.

Possible explanations include differences in patterns of smoking and susceptibility to the deleterious effects of tobacco smoke, as well as hormonal factors, according to Dr. Arora, an internist at McLaren Regional Medical Center in Flint, Michigan.

Using histologic codes, the investigators identified all cases of small cell lung cancer in the Surveillance, Epidemiology, and End Results (SEER) database among white and African American patients between the years 1973 and 2005.

Analyses were based on 70,886 patients with small cell lung cancer. About 91% were white and 55% were male.

During the study period, the male-to-female ratio in the proportion of all lung cancers that were of small cell type fell from 2.6 to 0.9, which mainly reflected a rise among women, Dr. Aurora said.

Age at presentation did not differ by sex. But women were more likely to have disease that was limited in stage (that is, confined to one hemithorax) at diagnosis than were men (35% vs. 30%).

And although cancer-specific survival improved for both sexes over time, it was consistently longer for women than for men. At the end of the study period, 2-year survival was approximately 20% among women, vs. 15% among men.

“We all know that small cell lung cancer is very closely related to smoking,” Dr. Arora commented. Hence, differences between the sexes in smoking patterns may explain some of these findings.

“Females began smoking 20 years after males,” she noted, and their smoking rates have been slower to decline. In addition, “females are more prone to tobacco effects: They are 1.5 times more likely to develop lung cancer than males with the same smoking habits.”

The study did not use multivariate or stage-stratified analysis, Dr. Arora said; hence, the less-extensive disease of women at presentation may have contributed to their better survival. Nonetheless, this finding “begs the question of a possible hormonal factor.”

Study results for race showed that the proportion of all lung cancers that were of small cell type was consistently lower among African American patients than among white patients throughout the study period. As of 2005, the value was 9% compared with 12% for white patients.

Age at presentation was younger among African American patients than among white patients. For example, roughly 50% of African American patients received their cancer diagnosis before age 64, compared with 40% of white patients. But the two racial groups did not differ with respect to the stage at diagnosis or cancer-specific survival.

Here, again, smoking patterns and susceptibility may explain some of the observed differences, according to Dr. Arora.

On the one hand, African American smokers smoke fewer cigarettes daily than do their white peers and start smoking later in life, she said. But “because of their lower quit rates, their prevalence of smoking is higher.” Also, they smoke more menthol cigarettes, which have higher levels of tar than the nonmentholated kind.

“On top of that, there is a race effect,” Dr. Arora noted. “African Americans are 1.8 times more susceptible than whites to developing small cell lung cancer with the same amount of smoking.”

Dr. Arora reported that she did not have any relevant financial conflicts.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

不列颠哥伦比亚省温哥华(EGMN)——美国胸内科医师学会年会上报告的一项回顾性分析显示，小细胞肺癌(SCLC)表现在不同性别和种族中存在差异。

研究者通过组织学编码来查找监测、流行病学和最终结果(SEER)数据库中1973年~2005年间所有的白人和黑人SCLC病例，共涉及70,886例SCLC病例。约91%为白人，55%为男性。

研究期间，所有SCLC病例中男性和女性比例之比从2.6降至0.9，反映出女性发病率增加。诊断年龄无性别差异，但诊断时被诊断为局限期病变(即局限于单侧肺部)的女性比例高于男性(35%对30%)。尽管癌症特异性生存率在两种性别中均随时间而改善，但在女性中一贯更长。本研究结束时，2年生存率在女性中约为20%，而在男性中为15%，这可通过吸烟模式方面的性别差异加以解释。在吸烟年龄上，女性比男性晚20年，并且女性吸烟率一直下降缓慢。此外，女性更易成为吸烟的受害者：女性发生肺癌的风险是具有相同吸烟习惯的男性的1.5倍。

总之，与男性相比，女性在诊断时的病变范围较为局限且生存率更佳。黑人患者的诊断年龄较白人患者年轻。与白人患者相比，在黑人患者中，SCLC病例占所有肺癌病例的比例较小。这些结果或可通过吸烟模式和吸烟危害易感性方面的差异以及激素因素加以解释。

研究者声明无相关经济利益冲突。

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