Genetic differences revealed by SNPS play a role in risk, prevention and outcome for cancer

AACR SNPs Conference in Key Biscayne, Fla., is exploring those differences

The quarry for this chase is collectively known as single nucleotide polymorphisms, SNPs. Commonly referred to as "snips," they are considered the most common alteration found in our hereditary makeup, far exceeding the better-known genetic miscue, the mutation.

Tracking down and isolating SNPs, some believe, is tantamount to locating a holy grail for the study of human disease. Unlocking their mysteries not only would help explain why some individuals are at greater risk for disease, but also what drugs might be tailored to each person for prevention and treatment of specific ailments, such as cancer.

"With SNPs, we are beginning to isolate key genetic differences among individuals, with the hope of applying that knowledge so we can develop new and more rational approaches to the diagnosis, prevention and treatment of cancer," said Timothy Rebbeck, Ph.D., associate professor, Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine.

Dr. Rebbeck is program chair of "SNPs, Haplotype, and Cancer: Application in Molecular Epidemiology," sponsored by the American Association for Cancer Research (AACR), taking place September 13-17 in Key Biscayne, Fla. The meeting is bringing together an international group of scientists from a variety of disciplines to discuss the latest methods in the field as it relates to cancer.

"Since cancer is such a complex disease, based on numerous genetic and signaling miscues, these studies also may provide one of the best tools for understanding its etiology," said Dr. Rebbeck.

Studies presented at this special conference include genetic predictors for:

• mammographic breast density, which may have implications for breast cancer risk as well as breast cancer screening. In this study, scientists at the Keck School of Medicine at the University of Southern California discovered that women with a specific variant for a gene called AKR1C4 experienced greater mammographic breast density � a strong risk factor for breast cancer -- when undergoing estrogen and progestin therapy (EPT). Mammograms used in the study were obtained from 233 postmenopausal women aged 45-75 years who had participated in randomized trials with EPT, estrogen alone or a placebo.

• individuals who might respond better to compounds naturally found in cruciferous vegetables such as broccoli, cauliflower, cabbage and Brussels sprouts. Here, scientists at the North Shore-Long Island Jewish Research Institute in Manhasset, N.Y. are seeking to identify specific gene alterations in breast and cervical cancer patients that predict response to indole-3-carbinol (I3C) and its active by-product diiindolylmethane (DIM), chemicals previously identified as promising agents for cancer prevention in numerous studies.

• pharmacogenetics studies that assess why some individuals might experience more effective results from treatments than others. One study, led by scientists at the University of Minnesota, has demonstrated that variations in genes may determine the outcome and toxicity of treatments of myeloma patients. Another study, conducted by scientists with Children's Cancer Institute for Medical Research in Sydney, Australia, revealed that children with a particular gene variant may contribute to an improved response to chemotherapy, and hence decreased risk of relapse, in children diagnosed with neuroblastoma. A third study, led by scientists at Harvard School of Public Health, showed how another polymorphism may be a useful predictor for overall survival of lung cancer patients treated with platinum-based chemotherapy.

Dr. Rebbeck cautioned that scientists are just starting to scratch the surface of what's possible for the prevention, diagnosis and treatment of cancer, with the help of SNPs and haplotypes.

But the number of abstracts and scientists attending SNPs conferences, such as the one in Key Biscayne, underscore that the field is beginning to attract greater attention in the United States and overseas.

"The challenge we now face is how to translate the vast amount of information about the human genome to improve human health," said Dr. Rebbeck. "This conference represents an important next step in helping to achieve that goal."