Turkiye Klinikleri Journal of Biostatistics

.: ORIGINAL RESEARCH
An Application of Cox Mixed Cure Model for Breast Cancer Patients
Meme Kanserli Hastalar için Cox Karma İyileşme Modelinin Uygulanması
Şirin ÇETİNa, Özge PASİNb, İsa DEDEc, Ayşe ÜLGENd
aDepartment of Biostatistics, Gaziosmanpaşa University Faculty of Medicine, Tokat, TURKEY
bDepartment of Biostatistics, İstanbul University İstanbul Faculty of Medicine, İstanbul, TURKEY
cDepartment of Medical Oncology, Mustafa Kemal University Faculty of Medicine, Hatay, TURKEY
dDepartment of Biostatistics, Girne American University Faculty of Health Sciences, Kyrenia, TRNC
Turkiye Klinikleri J Biostat. 2021;13(2):131-7
doi: 10.5336/biostatic.2020-79287
Article Language: EN
Full Text
ABSTRACT
 Objective: Survival analyses are used in cancer research in the selection of treatment methods that may be effec-tive in survival time and in investigating prognostic factors. In the literature, Cox regression analysis was performed without inves-tigating whether the assumptions were met in survival analysis. The aim of this study is; to give information about the features of Cox mixed cure models and to show its application for breast cancer patients. Material and Methods: In our study, it was ob-served that breast cancer data did not provide the proportional hazard assumption. In addition, since the survival curve has a flattened tail after 72 months, this study was analyzed with a mixed cure model. In the model, cured and uncured patients are modeled separately. Results: In our study, the median survival time of the patients was found to be 72 months (95% confidence interval; 51.88-92.12). Progesterone receptor, estrogen receptor, c-erbB-2, age and lymph node were found to be a significant risk factor for the survival of breast cancer patients in cured and un-cured part (for all of them p<0.05). Conclusion: Nowadays, can-cer patients are more likely to recover. For this reason, we think that it would be appropriate to evaluate the survival analyses of cured and uncured cancer patients separately with a mixed cure model instead of Cox regression analysis in modeling the survival analysis of cancer patients.

Keywords: Mixed cure model; breast cancer; estrogen receptor; progesterone receptor
ÖZET
 Amaç: Kanser araştırmalarında, sağkalım süresinde etkili olabilecek tedavi yöntemlerinin seçiminde ve prognostik faktörlerin bulunmasında, sağkalım analizleri kullanılmaktadır. Literatürde, sağkalım analizlerinde varsayımların sağlanıp sağlanmadığı araştı-rılmadan, Cox regresyon analizinin yapıldığı görülmektedir. Bu çalışmanın amacı; Cox karma iyileşme modellerinin özellikleri hakkında bilgi vermek ve meme kanserli hastalar için uygulamasını göstermektir. Gereç ve Yöntemler: Çalışmamızda, meme kanseri verilerinin orantılı hazard varsayımını sağlamadığı görülmüştür. Ayrıca yaşam süresi eğrisi, 72. aydan sonra düzleşmiş bir kuyruğa sahip olduğundan bu çalışmada, karma iyileşme modeli ile analiz yapılmıştır. Modelde, hastaların iyileşmiş ve iyileşmemiş olanları ayrı ayrı modellenmektedir. Bulgular: Çalışmamızda, meme kanse-ri hastalarının iyileşmiş ve iyileşmemiş olanları ayrı ayrı modelle-nerek hastaların medyan sağkalım süresi 72 ay (%95 güven aralığı; 51,88-92,12) olarak bulunmuştur. Progesteron reseptörü, östrojen reseptörü, c-erbB-2, yaş ve lenf nodunun iyileşen ve iyileşmeyen bölümlerinde de meme kanseri hastalarının sağkalımı üzerinde an-lamlı bir risk faktörü olduğu görüldü (hepsi için p<0,05). Sonuç: Gün geçtikçe kanser hastalarının iyileşme olasılıkları artmaktadır. Bu sebeple kanser hastalarının sağkalım analizlerinin modellenme-sinde, Cox regresyon analizi yerine karma iyileşme modellerinin ayrı ayrı değerlendirilmesinin uygun olacağını düşünmekteyiz.

Anahtar Kelimeler: Karma iyileşme modeli; meme kanseri; östrojen reseptörü; progesteron reseptörü
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