Prognostic factors in curative intent stage I lung adenocarcinoma: a retrospective hospital-based cohort study

Abstract

Radiotherapy or surgery, depending on hospital specialisation status (ie, High Complexity Centres in Oncology [HCCO; hospitals with infrastructure, technology, physical facilities, equipment, and human resources suitable for highly complex specialised assistance], or Partial Hospital Complexity Centres in Oncology [PHCCO; hospitals with infrastructures and specialisation similar to that of HCCOs, but doing diagnosis and treatment for common cancers only], as per nomenclature used in Brazil), can increase overall survival in patients diagnosed with lung adenocarcinoma. However, many patients do not accept surgery because of comorbidities and personal preferences. In addition, the long time between diagnosis and treatment and the qualification of the hospital specialisation status might affect the outcomes for patients with lung adenocarcinoma. The aim of this study was to evaluate prognostic factors of overall survival in patients with stage I lung cancer adenocarcinoma diagnosed in the state of São Paulo, Brazil. This was a retrospective hospital-based cohort study including patients of both sexes, aged 18 years or older, diagnosed with stage IA or IB lung adenocarcinoma and undergoing radiotherapy or surgery between Jan 1, 2000, and Dec 31, 2015, in 75 hospitals in the state of São Paulo, Brazil. The variables analysed were sex, age, education level, health system (public or private), clinical stage at diagnosis, time of diagnosis (2000-05; 2006-10; or 2011-15), type of treatment, time between first contact with health-care services and diagnosis (up to 1 month; 1-2 months; or 2 or more months), time between diagnosis and start of treatment (up to 1 month; 1-2 months; or 2 or more months), and hospital specialisation status (HCCO or PHCCO). Multivariate Cox regression analysis was applied to assess the risk of death. The second model was elaborated using propensity score technique. Balancing variables were sex, age group, type of treatment (radiotherapy or surgery), and educational attainment (including individuals who did not attend school), considering hospital specialisation status as dependent variable. The matching was done by logistic regression with the k-nearest neighbour algorithm. 681 patients were included. The 5-year overall survival rate was 58·1% (95% CI 53·9-62·1%). In the conventional multiple Cox regression analysis, patients who underwent radiotherapy alone had a risk of death nearly three times higher than that of patients who underwent surgery only (hazard ratio [HR] 3·44 [95% CI 2·45-4·82]; p<0·0001). Patients treated in PHCCOs had a higher risk of death (HR 1·49 [95% CI 1·10-2·03]; p=0·01) than patients treated in HCCOs. Patients aged 60 years or older and male patients also had a higher risk of death than patients younger than 60 years (HR 1·36 [95% CI 1·00-1·85]; p=0·048) and female patients (1·52 [1·17-1·98]; p=0·002), respectively. The multivariate regression analysis using propensity score technique showed that patients treated in HCCO hospitals had a higher risk of death (HR 1·80 [95% CI 1·26-2·56]), as did patients for whom time between diagnosis and start of treatment was longer than 2 months (2·00 [1·33-3·00]). Patients diagnosed in 2011-15 had a lower the risk of death than patients diagnosed in 2000-05 (HR 0·60 [95% CI 0·38-0·94]; p=0·027; protective factor). Our results show that the most significant prognostication factors for risk of death in patients with lung adenocarcinoma were delay between diagnosis and start of treatment and treatment in PHCCO hospitals. Patients diagnosed after 2010 also had a lower risk of death than those diagnosed before 2010. Incorporation of better patient care techniques, staging technology, and postoperative care can potentially reduce the risk of death. Lower mortality in HCCOs is likely due to the higher availability of multidisciplinary teams, and better infrastructure and technological structure dedicated to the care of all types of cancers. Oncocentro Foundation and Hospital Alemão Oswaldo Cruz, São Paulo, Brazil.