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Overweight women often get less chemotherapy than needed

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     Cancer doctors often calculate the dose of chemotherapy drugs based on body surface area, (BSA) which is calculated from the height and weight of a person. Body surface area is often expressed in Meter Square and naturally the dose of chemotherapy to be used for a patient increases with weight of a person.

    When treating overweight women using chemotherapy, cancer doctors often ignore this the dose calculated by the BSA and tend to reduce the dose of chemotherapy drugs. This occurs because overweight women may require large doses depending on the BSA. The doses are often reduced due to their concerns about its toxic effects and altered drug disposition. This would compromise the care of these women as per research data published in the recent issue of Lancet.

    There is no sufficient data to support the notion that the calculated chemotherapy doses should be reduced in overweight women. It has been found by Marco Colleoni (European Institute of Oncology, Italy) and his colleagues in this study that for the patients who are obese with estrogen-receptor negative breast cancer it is detrimental to reduce the doses of chemotherapy.

    For pre-menopausal women with breast cancer, the relation between the body-mass index, chemotherapy dose reduction, estrogen receptor expression and outcome has been assessed by the researchers by reviewing data from four randomized trials. It was found by the researchers that less than 85% of protocol specified dose was received by a higher proportion of obese patients (97 out of 249) during the first course of chemotherapy as compared to patients with normal or intermediate BMI.
    Significantly better disease-free survival and overall survival was observed in obese patients with estrogen-receptor negative disease whose first course dose was greater than or equal to 85% than those who received less than 85%.

    However, a significant difference in the outcome was not observed in obese patients with estrogen-receptor positive breast cancer for whom the doses of chemotherapy were reduced as compared to those who were given the recommended doses of chemotherapy. It was also found by the researchers that more toxicity were not present in the obese patients who were treated with protocol doses of chemotherapy initially as compared to the obese patients who were given reduced doses.
    Dr Marco Colleoni concludes by suggesting that reduction in the doses of chemotherapy should be avoided for women with ER-absent or ER-low tumors.
    It was stated by Lars Holmberg (University Hospital, Uppsala, Sweden) in an accompanying comment that several stimulating questions has been raised by this report, like ……… what is the reason behind the interaction with hormone receptor status? Is the response to chemotherapy modified by obesity within the estrogen-receptor-negative subset?

    If new and ingenious ways are found by the scientists to address the intriguing hypothesis, which was raised by the data of Gelber, more knowledge could be gained.