Overselling technology, Avastin and Circulating Tumor Cells

For years, since the Nixon war on cancer, we’ve oversold our ability to treat cancer. This tendency continues today.

Health Affairs blog has a piece from the Manhattan Institute’s Paul Howard that criticizes the FDA’s revocation of the use of Avastin in breast cancer.  His point seems to be that the drug which in clinical trials has been shown not to improve survival and have significant toxicity appears to work in a small subset of patients.  At present, however, we have no reliable means of determining who will respond and who will only get side-effects.  This in a drug costing between $50,000 and $100,000/year.

The American Cancer Society’s Deputy Medical director Len Lichtenfeld has noted:

“But it is important to understand the decision was based on the advice of an independent panel of experts who noted that larger studies showed some women lives were actually shortened on the drug and that toxicities associated with the drug were significant,” Lichtenfeld says. “Meanwhile, the net benefit for women taking the drug was quite modest.”

“What we clearly need is a way for doctors to more accurately predict which women will have a better chance of benefiting from this important targeted therapy,” Lichtenfeld says. “Until that tool is developed, giving all women with metastatic breast cancer Avastin may harm more women than it helps.”

Howard also talks of using tests for circulating tumor cells (CTC’s) as a way to:

screen for cancer that can replace expensive or invasive tests like mammograms or colonoscopies; to tailor cancer treatments and adjust them based on how many or what type of CTCs are found in a patient’s bloodstream; or make physicians more comfortable adopting a “watch and wait” approach for elderly patients in cases where the underlying cancer may grow so slowly that it will never become life-threatening.

His analysis of the test is  incorrect.  While it may be useful in identifying those with more serious disease it does not appear to have utility as a screening test for early cancer.  When a tumor has reached the point that it’s cancerous cells are in the blood stream, the tumor is not  early  but rather one that is at high risk to  have spread and  metastasize.  I know of no study suggesting use of  CTC’s as a marker or screening test for early cancer–the ones most amenable to being cured.

Medicynical Note:  It would be of interest to know of Mr. Howard’s and Manhattan Institute’s pharmaceutical industry support.

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