Fitting Cure Rate Model to Breast Cancer Data of Cancer Research Center

Abstract

Background:The Cox PH model is one of the most significant statistical models in studying survival of patients. But, in the case of patients with long-term survival, it may not be the most appropriate. In such cases, a cure rate model seems more suitable. The purpose of this study was to determine clinical factors associated with cure rate of patients with breast cancer. Materials and Methods: In order to find factors affecting cure rate (response), a non-mixed cure rate model with negative binomial distribution for latent variable was used. Variables selected were recurrence cancer, status for HER2, estrogen receptor (ER) and progesterone receptor (PR), size of tumor, grade of cancer, stage of cancer, type of surgery, age at the diagnosis time and number of removed positive lymph nodes. All analyses were performed using PROC MCMC processes in the SAS 9.2 program. Results: The mean (SD) age of patients was equal to 48.9 (11.1) months. For these patients, 1, 5 and 10-year survival rates were 95, 79 and 50 percent respectively. All of the mentioned variables were effective in cure fraction. Kaplan-Meier curve showed cure model's use competence. Conclusions: Unlike other variables, existence of ER and PR positivity will increase probability of cure in patients. In the present study, Weibull distribution was used for the purpose of analysing survival times. Model fitness with other distributions such as log-N and log-logistic and other distributions for latent variable is recommended.

Survival probability and prognostic factors of Iranian breast cancer patients using cure rate model

“…However, despite the increased mortality rate in N2+ women than N1 women, no significant difference was observed between N1 and N2+cure rate in this study which may be related to the difference in the effect of other items of TNM system such as the size of tumor and distant metastasis in N1 group. In line with the results of the present study, Baghestani et al indicated that patients with the involvement of more than 10 lymph nodes had 12 months less survival and 24% more mortality. In another study, Baghestani et al showed a significant relationship between survival and lymph node involvement.…”

“…The results of the present study indicated that the rate of cure reduced to four times with an increase in tumor grade, mortality rate increased, and their survival reduced. Similar to the results of this study, Baghestani et al indicated that there is a significant relationship between the disease grade and survival of the patient …”

“…However, the cure rate in women with stage II was more than stage III although the difference was not statistically significant. Similar to this study, a significant relationship was confirmed between stage and survival . The results of this study indicated that the cure rate of patients increased with a decrease in tumor size.…”

“…The high rate of 5‐year survival in Iran indicated the optimal follow‐up and appropriate awareness on such a disease, compared to the total statistics in thedeveloping countries. However, due to an increase in its incidence and low survival rate of 8%, compared to the statistics in America and Europe, a more comprehensive planning is critical in this field . Furthermore, this study indicated that the cure probability of women <40 years and 41‐60 years was significantly more than in elderly women.…”

“…In the study of Mahood et al, no significant relationship was observed between the tumor size and total survival of patients. The results of other studies proved the reverse effect of tumor size on survival …”