A Study Of Association Between Common Risk Factors And Survival Of Breast Cancer Patients

Purpose: Breast cancer is one of the most important causes of cancer death in women. In recent years, both incidence and mortality of breast cancer are increasing, and 250,000 women will be newly diagnosed as breast cancer and about 60,000 women will die from breast cancer every year in China. Most studies believed that patients with more lymph node metastasis, larger tumor diameter, lower histological grade and late TNM stage will have a bad survival. Some survival cohort study have also considered that some common risk factors such as smoking, overweight or obese, numbers of pregnancy and age of last birth may reduce survival rate of breast cancer patients. However, large samples of survival cohort study is relatively rare in China so we follow up for cases of breast cancer and establish a case-based survival cohort study to explore the influence of common risk factors on survival of breast cancer patients in order to reveal the role of risk factors in the occurrence and development of breast cancer.Method: we collected cases that performed surgery in Tianjin Medical University Cancer Hospital from January 1, 2003 to December 31, 2013 and all the cases were confirmed by pathology. The demographic information and risk factors were collected by professional personnel. All the clinical data and information of pathology and treatment were obtained from medical records. Then we followed up the survival status(alive or death), recurrence or/and metastasis after surgery or not, time of recurrence or/and metastasis of patients diagnosed form 2003 to 2010 years and this information would be used to calculate overall survival(OS) and disease free survival(DFS). The data were input through Access of Microsoft and transferred to SPSS 17.0. Chi square test was used to analyses association between clinical characteristics and risk factor score, and univariate and multivariate logistic regression to analyses association between risk factors and clinical factors, and univariate and multivariate Cox regression was used to analyses effects of clinical factors, common risk factors and risk score on OS and DFS of breast cancer patients. We considered P?0.05 as statistically significant difference.Result: A total of 11358 patients with breast cancer were included and 5157 patients were followed up and 343 patients died and 421 cases were recurrence and / or metastasis. We found patients with late TNM stage, tumor diameter bigger than 2.5 cm, ER negative and PR negative had a worse OS and DFS, which was in agreement with results of other researches. Multivariate Cox regression showed that only the number of pregnancy have an impact on OS of breast cancer and compared to patients who had more than 2 times pregnancy, patients who had less than or equal to 2 times pregnancy had a decreased total mortality(Hazard Ratio =0.69, P = 0.04). In addition, the result of multivariate Cox regression showed that patients with BMI?25 had a worse DFS than patients with BMI< 25(HR=1.32, P = 0.04), and stratified results showed that significant differences between the two groups only had been found in ER negative and PR negative patients(HR=1.57, P = 0.02; HR=1.47, P = 0.05).There were 11 risk factors scored, from 0 points to 10 points, and the average score of 4.78 + 1.63 points. Comparing with patients in the low risk group, patients in the moderate risk group and the high risk group had a better OS and the higher risk score, the better OS. In stratified analysis, the same results were only found in ER positive and PR positive patients. No significant difference was found between DFS of the low risk group and moderate risk group as well as high risk group, but ER negative and PR negative patients in the moderate risk group and high risk group were more likely to have a DFS than low risk group. On the contrary, ER positive and PR positive patients in the moderate risk group and high risk group were more likely to have a better DFS than low risk group though there was no significant difference.Conclusion: On one hand, breast cancer patients with the number of pregnancy more than 2 times comparing to those with 2 times or less than 2 times had a poor survival prognosis, and overweight patients, especially negative ER and PR negative patients were more likely to have recurrence and / or metastasis. On the other hand, ER positive and PR positive patients with more risk factors scores had better OS, while the DFS of patients in ER negative and PR negative patients was worse.