Abstract

Objectives: The current article aims to derive the joint mean-variance fitted models for the overall survival time from stage III non-small cell lung cancer patients. In addition, it aims to identify the determinants of the overall survival time, based on 239 subjects with 23 factors / variables.

Background: Overall survival time is positive, heterogeneous, and non-normal which is generally modeled either by the Log-normal or the gamma models. Little is known about the joint mean-variance models for overall survival time from stage III non-small cell lung cancer patients.

Materials and Methods: The present article is based on the secondary data on 239 stage III non-small cell lung cancer patients along with 23 explanatory factors/ variables. The overall survival time of 239 patients is heterogeneous, positive, and gamma distributed. Therefore, statistical joint generalized linear gamma or Log-normal models are considered to analyze the overall survival time.

Results: The overall survival time (OST) of stage III non-small cell lung cancer (NSCLC) patients is higher for the never/ex-smokers (P =0.049) than for the current smokers. The OST is higher for the stage III NSCLC patients having large cell carcinoma or other (P =0.110) than the patients having adenocarcinoma or squamous cell carcinoma. It decreases (P=0.026) as the number of positive lymph node stations increases. It is higher (P=0.072) of the lung cancer patients having N-stage at level N3 or Nx than the others. It is also higher of the lung cancer patients belonging into standard concomitant (P=0.050), or standard sequential (P=0.026), or sequentialselected (P=0.003) group than the no chemo group. The OST is higher (P<0.01) of those lung cancer patients whose start of the study year are earlier. It increases (P = 0.001) as the equivalent dose increases. It decreases (P<0.01) as the overall treatment time increases. There are many more significant determinants of the variance of OST.

Conclusions: The overall survival time from stage III non-small cell lung cancer patients is identified as heterogeneous and gamma distributed. Most of the present findings, specially the variance determinants of overall survival time are completely new in the literature.

Keywords: Chemotherapy; Gamma model; Overall survival time; Stage III non-small cell lung cancer; Non-constant variance