The most extensive analysis ever of metastatic tumors has dredged up hope for cancer patients and their physicians. Metastatic cancer can travel from the primary tumor to everywhere in the body and scientists have long believed that the metastasis in, say, the lungs is genetically different from the metastasis in, say, the liver. That would make it impossible to treat all the cancers with the same molecular targeted therapy.
A study in Science by Johannes G. Reiter, of Stanford University School of Medicine and colleagues, found that untreated metastases in a cancer patient are caused by the same genetic mutation, no matter where the cancer winds up. That potentially means that a physician might be able to take one biopsy from one organ and treat all the organs with one molecularly targeted therapy.
The study looks at 76 untreated metastases from 20 patients and inferred cancer phylogenies for breast, colorectal, endometrial, gastric, lung, melanoma, pancreatic, and prostate cancers. “We found that within individual patients, a large majority of driver gene mutations are common to all metastases,” the study states. “Further analysis revealed that the driver gene mutations that were not shared by all metastases are unlikely to have functional consequences.”
As Stat reports, that finding “bodes well for targeted therapies, because it means a single drug should work against all of a patient’s metastases—and it is the metastases, not the primary tumor, that are responsible for 90% of cancer deaths.”
A good response should not be mistaken for a cure, though. “Just as most cancers eventually outwit drugs that target causative mutations in the original tumor, so metastases would likely do that as well,” Stat reports.
On the other hand, says study co-author Christine Iacobuzio-Donahue of Memorial Sloan Kettering Cancer Center, “the implication is that anything you find might be actionable and you should go for it. The driver mutation is in all the cells of that metastatic lesion and every other, and you can expect a good clinical response.”