Background: Taking patient centeredness into account is important in healthcare. The European Cancer Consumer Quality Index (ECCQI) is a validated tool for international benchmarking of patient experiences and satisfaction. This study aimed to further validate the ECCQI in larger and more uniform groups of high volume tumours such as breast and prostate cancer. A second objective was the verification of the influence of cultural factors of the country to determine its possible use in international benchmarking. Methods: Data from two survey studies in eight European countries were combined. Socio-demographic correlations were analysed with Kruskall-Wallis and Mann-Whitney tests. Cronbach’s alpha was calculated to validate internal consistency. Influences of masculinity (MAS), power distance (PD) and uncertainty avoidance (UA) were determined by linear regression analysis in a general model and subgroup models. Results: A total of 1322 surveys were included in the analysis (1093 breast- and 348 prostate cancer patients). Cronbach’s alpha was good (α ≥ 0.7) or acceptable (0.5 ≤ α ≤ 0.7) in 8 out of 9 questionnaire categories, except in the category ‘Safety’ (α = 0.305). Overall ECCQI scores ranged from 22.1 to 25.1 between countries on a 1–35 scale (categories had a 1–4 scale). In certain subcategories such as ‘Organisation’ (range 2.2 vs 3.0) and ‘Supervision & Support’ (range 3.0 vs 3.8) a large difference was observed between countries. Differences in ‘Overall opinion’ were however small: mean scores of 3.7 vs 3.9, whereas median scores were all the maximum of 4.0. Power distance was positively associated with higher patient satisfaction scores whereas Uncertainty avoidance was negatively associated with these scores. Masculinity was only associated with patient satisfaction scores in lower educated patients. We found the highest impact of culture on overall scores in Hungary and Portugal and the lowest in Romania. Conclusions: The ECCQI shows high internal consistency in all categories except ‘Safety’. Especially in separate categories and overall ECCQI scores the questionnaire showed discriminative value. This study showed a positive correlation of power distance and a negative correlation for uncertainty avoidance in some countries. When using the ECCQI for international benchmarking these two dimensions of culture should be taken into account.