Posted by Keith Galloway on Fri, Nov 13, 2009 @ 08:25 AM
To determine the appropriate chemotherapy dose for individual patients, oncologists most often turn to the standard of body surface area (BSA). But relying on BSA alone can result in under-dosing or over-dosing because this standard measurement does not provide enough specific, personalized information about the patient. Individual patients not only absorb and metabolize drugs differently, but the rates of drug absorption and clearance in an individual change day to day, week to week.
Testing of blood drug levels, by contrast, provides the oncologist with more accurate information about how a patient's body is responding to a standard dose. It also gives the physician a tool for monitoring patient response and making any necessary adjustments over time. Blood testing greatly increases the likelihood that the oncologist prescribes the optimal dose and maintains it.
How does such personalized chemotherapy blood testing and management work? At the start of chemotherapy, the oncologist prescribes a test designed to determine the actual blood level of a specific cancer drug in his patient. After a blood draw, the blood sample is sent to a laboratory for analysis. The results, combined with clinical exams, allow the physician to draw conclusions about the efficacy and safety of the initial dose. If the dose is too low or too high, adjustments can be made accordingly.
In a study published in the Journal of Clinical Oncology, a group of metastatic colorectal cancer patients treated with a BSA-based dose of 5-fluorouracil (5-FU) were tested for blood drug levels. The patients received a wide range of dose adjustments in order to reach optimal 5-FU plasma levels during subsequent treatment cycles. The process was repeated over a period of several weeks. Compared with a control group given standard fixed dosing, the dose-adjusted group achieved higher response (33.7 percent versus 18.3 percent) and survival rates (22 months to 16 months).
Blood testing gave oncologists the data they needed to increase dose intensity in the studied patients, thus enhancing efficacy. At the same time, it enabled them to avoid the toxicity that could lead to debilitating side effects. Ninety-four percent of study-group patients received the target dose with dose management. For those patients receiving personalized therapy, the elusive balance between efficacy and safety was achieved.
Posted by Keith Galloway on Fri, Nov 06, 2009 @ 10:04 AM
The goal of every oncologist is to deliver chemotherapy to patients at doses that are the most efficacious without causing severe toxic effects. The optimal dose lies between doses that are too low to produce a positive response and those that are too high to avoid toxicity.
Compared to other fields of medicine, however, oncology tends to have among the lowest efficacy rates. One reason for this may be that oncologists often err on the side of under-dosing to minimize debilitating side effects. But if a patient receives levels of chemotherapy that are too low, the results are little to no therapeutic response, continued growth of tumors, developing resistance to the drugs, and a higher risk of disease recurrence.
Oncologists have been trained to administer and believe they are administering the maximum tolerated dose (MTD) in order to achieve and maintain the optimal level of a given cancer drug in patients' bloodstream. However, to date, doctors have not had the appropriate tools to verify whether the dose they give is actually the MTD for their individual patient. If the drug dose is too high, the patient suffers from excessive toxicity which can lead to severe adverse reactions and compromised immunity in patients, resulting in termination or interruption of treatment.
Dose optimization offers a solution to these ongoing challenges facing oncologists and patients. With personalized dose management, based on the testing of chemotherapy blood levels, oncologists can more reliably attain the optimal dose for each patient and maintain dose optimization throughout the course of treatment.
How is dose optimization achieved? Through blood testing of individual patients, oncologists can more accurately determine the most effective dose for the individual patient considering age, gender, weight, health status, genetics and other key factors. Repeat testing allows the oncologist to not only account for the fact that each patient absorbs, metabolizes, and eliminates drugs differently but also at a rate that varies over time. Adjustments in dosing can be made accordingly.
The benefits of dose optimization are multiple: more effective dosing, greater therapeutic response, and higher survival rates. Reduced toxicity also translates into better quality of life for patients.
With a tool like Personalized Chemotherapy Management Assays, dose optimization can become standard practice, raising the efficacy of treatment and improving outcomes for cancer patients.