Survival Rate Estimation of Cervix Cancer Patients Using K-M and W-K-M

Abstract

In clinical practice, survival curves show the fraction of patients who experienced the outcome of interest. Survival rates are estimated using survival curves which are determined using Kaplan- Meier method. However, when in case of large number of censored observations, Kaplan- Meier method tends to provide biased estimates. This research article compares widely used Kaplan-Meier (K-M) method & Weighted Kaplan-Meier (WKM) method as a suitable substitute of KM while dealing with the issue of heavy-censoring by applying them on real life data of 900 Cervix Cancer patients diagnosed and treated during 2012-2018 at Rajiv Gandhi Cancer Institute and Research Center, Delhi are analyzed. Then, Five year survival rate of the patients is estimated by using K-M and WKM methods. It was observed that out of 900, 547 (60.78%) patients experienced the event till last follow up and rest of the patients (39.22%) patients were censored of which 187 are lost to follow up and 166 are alive. Median survival time is found to be 65.33 months. Subsequently, 1 year, 2 year, 3 year, 4 year and 5 year survival rates are found to be 81%, 66%, 47%, 33% and 21% respectively by K-M whereas they are found to be 78%, 63%, 63%, 44%, 29% and 19% by WKM. The result of this study shows that in absence of censoring assumption of Kaplan- Meier, Kaplan-Meier method gives biased survival estimations. These estimates are higher than the real estimates. In such cases, Bias can be decreased by using WKM which gives suitable weights to the observations and results in precise understanding.