Cancer tumors exhibit an accumulation of mutations in DNA (something distinct from inheriting a mutation that increases one’s likelihood of getting a given type of cancer [previous post]). This results in tumors having particular genetic profiles in different people even if the people are diagnosed as having the “same” cancer. Sometimes the effectiveness of a treatment can be predicted according to the genetic profile of the tumor. Clinical researchers are gathering data in the hope of classifying the genetic profiles into groups in relationship to their response to available treatment options. Continue reading
BRCA1 and BRCA2 mutations are more common in certain populations (e.g., people of Ashkenazi Jewish descent) than others. Closer monitoring or prophylactic measures might be undertaken following positive tests (by genomic sequencing) for those mutations. Genomic studies are identifying other genetic variants of biomedical significance that are more common in people of specific regions and thus of people whose ancestry traces to those regions (e.g., Genovese et al. 2010). Continue reading
New research on an enzyme [PAD2] linked to cancer development shows that 37 percent of mice that produce excessive quantities of the enzyme developed skin tumors within four to 12 months of birth, and many of these growths progressed to highly invasive squamous cell carcinoma, a common form of skin cancer.
This research built on earlier work suggesting Continue reading
“All cancers are genetic,” the genetic oncologist might say. If asked to elaborate, they might explain that “all cancers begin when one or more genes in a cell are mutated (changed), creating an abnormal protein or no protein at all” (cancer net). If asked what that means for relatives, they would note that “only about 5% to 10% of all cancers result directly from gene defects… inherited from a parent” (American Cancer Society). Continue reading
Sometimes experimental treatments for cancers are effective for only a small number of patients—”exceptional responders.” Sequencing of their cancers may reveal a genetic mutation that explains why the drug was effective (Kolata 2014). Future patients can have their cancer genomes analyzed to determine whether an effective drug is known for their profile of mutations.
- Drug companies discontinue production of the drug because it works for so few.
- “Researchers… see hundreds of mutations in a cancer and none will explain a patient’s response to a drug,” molecular oncologist quoted in Kolata (2014)
- Cancer centers lure patients using the possibility that they are the rare exceptional responders.
Medical oncologists describe a cancer or likelihood of cancer as familial if a family genealogy shows, say, breast or ovarian cancer in female relatives. They would suspect a gene passed down but not know its identity. A hereditary cancer or likelihood of cancer is when a person is shown, by genetic testing, to carry a specific gene, such as BRCA1 or BRCA2, that has been linked to a much higher frequency of incidence of the cancer. Medical oncologists suggest that the distinction between familial and hereditary cancers will eventually be eliminated as the genes for the familial cancers are identified. Continue reading
In any quantitative analysis that associates a trait with some measurable genetic or environmental factors, the genetic factors are factors for difference. That is, a difference in the factor is associated, when viewed across a population of individuals, with a difference in the trait. These differences that a factor-for-difference makes ( as we ambiguously say in English) in the trait depend on the context (i.e., they are “local”) and that context has dynamics, which may or may not be restructured if the factor is taken beyond the boundaries of the local context.
Given that quantitative analysis of variation for a trait concerns genes or other factors for difference, what can be reasonably promised regarding genes and the development of a trait in an individual? Continue reading