Scientist disappointed of cancer treatment research
Scientists are reporting what could be very bad news for efforts to personalize cancer treatment based on each person’s genes.
They found great differences from one place to another within the same tumor in which the genes are active or mutated. There were also differences in the genetics of the primary tumor and where the cancer has spread.
This means that simple biopsy that doctors rely on the selected drugs are probably not give an accurate picture of the biology of cancer. It also means that the cancer will not be as simple as many had expected.
By analyzing tumors in unprecedented detail, “we find that the higher you go,
rather than find,” said study leader, Dr. Charles Swanton Cancer Research UK London Research Institute England. ”It’s like going from a black and white television with four pixels in a color TV with thousands of pixels.”
However, the result is a blurred image of how to treat the disease.
The study was published in the New England Journal of Medicine on Thursday.
This is a reality check for the “excessive optimism” in the area dedicated to the fight against cancer with new genes that target the drugs, Dr. Dan Longo, an associate editor of the magazine, wrote in an editorial .
About 15 of these drugs on the market today and hundreds more are under study, but have had limited success. And the new study may help explain why.
The scientists used gene sequencing to a degree that has not been done before studying primary tumors and the places where it divides into four patients with advanced kidney cancer. They found that two thirds of the mutations detected were not present in all areas of the same tumor. They also were surprised to see different mutations in the same part of a tumor to another.
This means that a single biopsy would reveal only a minority of the mutations.However, it is unclear whether the biopsies done to improve the accuracy, or how much and how often you should have.
Although the study focused on kidney cancer, independent experts said the findings should apply to other cancers such as breast, lung and colon. And research suggests that this is so.
“This is an important document,” said Dr. Gordon Mills, co-director of the Institute for Personalized Cancer Therapy at the University of Texas MD Anderson Cancer Center.
Doctors have been offering genetic testing of patients for several years and have a database of about 4000 results of the tumor samples. So far, about 40 percent of breast cancers showed inconsistencies between genes that are active in the primary tumor and those who are active, where the cancer has spread, said Mills.
It costs $ 5,000 to $ 10,000 for the analysis of the genetic basis of primary tumor, and about 10 times to make the kind of scientific evidence in the British study did, said Mills.
And if it does, “we will find a wealth of information we do not know what to do about” as a biopsy, suggests a certain mutation is the engine of another biopsy suggests cancer and another is, in which he said.
It also takes valuable time. Swanton said the sequencing of the genome of a cancer patient made a complete very large four months. The amount of time required is down, but this type of personal analysis is still far from being available at the clinic said.