ASSESSMENT OF THE TIME-TRADEOFF VALUES FOR PROPHYLACTIC MASTECTOMY OFWOMEN WITH A SUSPECTED GENETIC PREDISPOSITION TO BREAST-CANCER

Background. Female carriers of the breast-cancer-susceptibility genes BRCA1 and BRCA2 are at high risk for breast cancer (85%). They face th e choice between prophylactic mastectomy (PM) and breast cancer screen ing. For this treatment choice, a shared-decision-making program was d eveloped. In this program, the time tradeoff (TTO) was used to assess preferences for PM. Purpose. Assessment of the feasibility, constant p roportional tradeoff, and reliability of using the TTO for this purpos e. Methods. Fifty-four women suspected to carry the BRCA1/2 mutation w ere provided with comprehensive relevant information. Their preference s for PM were assessed on two occasions. Discrepancies between prefere nces indicated by the two tests were resolved by testing a third time. The preferences assessed on the last occasion were used for individua l decision analyses. In order to test constant proportional tradeoff, the TTO consisted of four items with different numbers of life years. Results. Forty-two women (78%) completed the TTO twice and nine women (17%) performed the test a third time. Three women (5%) completed the TTO only once. The mean TTO value for PM at the last replication was 0 .69 (SD = 0.30). Violations of constant proportional tradeoff were sig nificant: the largest tradeoffs were recorded for the shortest duratio ns. Pearson's correlation coefficient between the TTO values for the t wo last sessions was 0.96. Conclusion. Assessment of individual prefer ences by the TTO in this patient group is feasible and reliable. There fore, the TTO can be used in clinical settings to elicit treatment pre ferences of women proven or suspected to have a genetic predisposition to breast cancer.