A hundred members of the general public will be recruited in the Netherlands and in Sweden to participate in time trade off (TTO) interviews. In Sweden in order to try to match the socio-demographic profile of women suffering from HER2+ MBC, recruitment will be aimed at females aged over 50. In the Netherlands participants will be from both genders, and of mixed age, ethnicity, education and employment status categories. In Sweden, interviews will be conducted in Stockholm, Tyresö and Malmo. In the Netherlands, interviews will be conducted in Rotterdam, Amsterdam and Colmschate.