Science：癌细胞的“种族歧视”

　　

生物通报道，2007年Science杂志的一篇曾报道癌症与种族间的关联，癌症对不同的人种会产生不同的反应和预后。今天，Loyola大学的一名女科学家再度发表研究进展，报道癌症与种族间的关联。

 

2007年科学家们就已经发现，黑人妇女相对白人妇女更易得乳腺癌，但是在死亡率上却相反，黑人妇女患乳腺癌的死亡率比白人妇女高。有科学家质疑这一结果可能与黑人以及白人妇女所接受的健康治疗的差异有关，这些差异不源于生物学而源于环境的差异。

 

然而，今天，一项新的调查研究显示，有些癌症，如肺癌和白血病不存在种族差异；而部分癌症，如乳腺癌，前列腺癌和卵巢癌却存在种族差异。

 

Loyola大学的肿瘤专家Kathy Albain从1974年到2001年间，对20000名癌症患者进行追踪调查，所涉及的癌症种类包括：乳腺癌，肺癌，结肠癌，卵巢癌，前列腺癌，多发性骨髓瘤，淋巴癌和白血病。患者们接受相似的治疗，在某些程度上减轻经济地位的差异。

 

研究发现，大部分的癌症不存在种族差异，但是有3种癌症存在明显的种族差异，乳腺癌，前列腺癌和卵巢癌。绝经前早期乳腺癌患者中，非洲裔美国妇女存活10年的只有68%，而其他种族的人群高达77%（大部分是高加索人）。而晚期卵巢癌患者中，非洲裔美国人平均寿命只有1.3年，而其他种族的人群又2.3年（大部分是高加索人）。晚期前列腺癌患者中，非洲裔美国人的平均寿命是2.2年，而其他种族的人是2.7年。这些研究成果刊登在Journal of the National Cancer Institute上。

 

Kathy Albain表示，值得庆幸的是，大部分的癌症没有种族差异。这给治疗带来便利。她猜测，这些差异可能源自两个人种在肿瘤生物学，激素应答和基因上的差异。

（生物通 小茜）

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生物通推荐原文阅读：

Cancer Does Discriminate

By Jennifer Couzin-Frankel

For years, researchers have known that race is a factor in cancer survival. Black women are less likely than whites to get breast cancer, for example, but much more likely to die from it (Science, 2 February 2007). How much of this difference stems from unequal access to health care, such as regular screening and aggressive treatment, and how much is rooted in biology? A new study that looks back at dozens of cancer clinical trials concludes that for some cancers, such as lung and leukemia, race makes no difference, while for others, such as breast, prostate, and ovarian, it does.

Oncologist Kathy Albain of Loyola University Chicago in Illinois felt that one way to get a big-picture view of the link between race and cancer survival was by combing through a vast network of clinical trials. So she turned to the Southwest Oncology Group (SWOG), one of several cooperative groups in the United States that oversees large, multicenter trials for a variety of cancers in which all the participants get the same level of care, and many receive the same treatment. Albain and her colleagues focused on 35 large SWOG trials that ran at some point between 1974 and 2001, and that included nearly 20,000 adults. The trials covered eight cancers: breast, lung, colon, ovarian, prostate, multiple myeloma, lymphoma, and leukemia. Albain's team examined how African-American participants fared, adjusting for potential confounding factors such as weight and socioeconomic status (estimated from ZIP codes).

 

For most of the cancers, race made no difference in survival. But for three--breast, prostate, and ovarian--it mattered. In early-stage premenopausal breast cancer, for example, 10-year survival rates were 68% for African Americans versus 77% for all other patients (mostly Caucasian) in the trials. For advanced ovarian cancer, median survival was 1.3 years for African Americans and 2.3 years for the rest of the participants. And for advanced prostate cancer, it was 2.2 years versus 2.7 years, the group reports online today in the Journal of the National Cancer Institute.

 

On one hand, the results are reassuring because for many common cancers, race made no difference to the outcome, says Albain. She believes the answer to why differences exist for three cancers lies in an interaction among tumor biology, hormonal responses in the patient, and genes that could affect how drugs, such as certain chemotherapies, are metabolized.

 

One of the questions that's dogged the study of racial disparities in cancer has been how much is due to access to care, notes Timothy Rebbeck, a cancer epidemiologist at the University of Pennsylvania. But here, "disparities persist even in the presence of a standard treatment." Furthermore, the three, sex-specific cancers have been fingered in other racial-disparity studies, he says.

 

One concern, says Peter B. Bach, a physician and epidemiologist at Memorial Sloan-Kettering Cancer Center in New York City, is whether deaths in the trials were invariably due to cancer--as opposed to some unrelated disease to which African Americans are more susceptible, such as diabetes. But Albain notes that if this were the case, her group would have seen disparities across all cancers--not just the few they detected. She's now scrutinizing gene expression patterns and other features of banked tumors for more clues.