NewsRx.com
May 8, 2008
Can a blood test improve treatment outcomes for colorectal cancer patients? Recently published studies indicate that personalized chemotherapy dose management -- measuring drug levels in patients' blood and adjusting them for optimal dosing -- can substantially reduce severe toxicity and improve efficacy in colorectal cancer.
A Phase III randomized study of 208 colorectal cancer patients, by Erick Gamelin, M.D., Ph.D. et. al., was published in the May 1 issue of the Journal of Clinical Oncology (JCO). It found that metastatic colorectal cancer patients whose dose of 5-fluorouracil (5-FU) was personalized based on results of regular blood tests experienced reduced severe toxicities and nearly doubled response rates compared to patients who received standard 5-FU dosing based on body surface area. Additionally, patients who received personalized dosing experienced a 48 percent relative improvement in survival at two years. 5-FU is the cornerstone chemotherapy in most treatment regimens for this type of cancer.
The current standard-of-care in dosing 5-FU is based on body surface area (BSA) and is calculated using patients' height and weight. In the JCO study, personalized dosing was based on blood tests to measure the actual level of the drug. The study demonstrated that only 25 percent of colorectal cancer patients achieved optimal chemotherapy blood levels when dosed by BSA. Seventeen percent of the BSA-dosed patients received toxic levels of the drug, while 58 percent were under-dosed.
The JCO study, "Individual 5-fluorouracil dose adjustment based on pharmacokinetic follow-up compared with conventional dosage: Results of a multicenter randomized trial of patients with metastatic colorectal cancer," evaluated patients being treated with 5-FU in combination with leucovorin. Half of the patients were dosed with 5-FU based on BSA. The other half were initially dosed based on BSA, with subsequent cycle doses adjusted based on blood tests that measured the actual concentration of chemotherapy in the patients' blood plasma. The primary endpoint was tumor response; the secondary endpoint was treatment tolerance.
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