TK1 and posterior cortical atrophy: Thus, assuming that all PCa were detected simultaneously with the TK1 + PSA measurement (Table 3, multivariate analysis B), the difference in OS between 1 and 4, 2 and 4 and 3 and 4, which was significant in univariate analysis, was also significant in multivariate analysis (p = 0.008; p = 0.007; p = 0.028, respectively).