Survival of Breast Cancer Subtypes

In a clinical study, survival of mixed lobular and ductal carcinomas of breast cancer was compared with a series of patients with pure invasive ductal ones. One hundred and thirty-two patients, ninety-eight with ductal carcinomas and thirty-four with mixed who had been treated by modified radical mastectomy, were followed for 10 years [26 (link)]. Survival data were available for all patients with a minimum of five-year follow-up period. At the end of follow-up time, their survivorship was assessed in relation to the histological type of tumor. The data are presented in Table 2.
The OR and RR of five-year mortality for the mixed versus ductal type were, respectively: $$OR=\frac{a\cdot d}{b\cdot c}=\frac{26\cdot 60}{8\cdot 38}=5.13,$$
$$RR=\frac{a\left(c+d\right)}{c\left(a+b\right)}=\frac{26\cdot 98}{38\cdot 34}=1.97$$
Moreover, the 95% Confidence Intervals (CIs) of OR and RR were: 95% CΙ OR (2.11, 12.50) and 95% CI RR (1.45, 2.69).