Timing key in cancer chemotherapy.

Timing key in cancer chemotherapy

The body is a symphony of rhythms--the rate of cell division, the timing of hormone production and the patterns of brain waves all change throughout the day and night. Cancer chemotherapy can be made more effective by taking the body's timing into account, says William J. M. Hrushesky of the University of Minnesota in Minneapolis.

At the San Diego seminar and in the April 5 SCIENCE, Hrushesky reported that the timing of a two-drug sequence in women with advanced ovarian cancer markedly affects the onset of complications. The women were given adriamycin and cisplatin, two powerful anticancer drugs that can alter blood cell counts, permit infection and cause bleeding and anemia.

Hrushesky tried 26 women on both a 6 a.m. adriamycin, 6 p.m. cisplatin schedule and a 6 a.m. cisplatin, 6 p.m. adriamycin schedule. Twenty of the women had complications on the second schedule, compared with 11 on the first; the results echo rodent studies that show adriamycin is most toxic late in a rat's "activity cycle' and cisplatin is most toxic around the time of awakening.

The body's rhythmicity can also be used to monitor adverse reactions to chemotherapy. Hrushesky has found that a disturbance in the normal rhythmic pattern between breathing and heartbeat can be used as an early indication of heart cell death and may prove useful as a clinical screening test for toxic effects of chemotherapy.