A study of smoking, p53 tumor suppressor gene alterations and non-small cell lung cancer

Causal effects of time-dependent treatments in older patients with non-small cell lung cancer

Background

Treatment selection for elderly patients with lung cancer must balance the benefits of curative/life-prolonging therapy and the risks of increased mortality due to comorbidities. Lung cancer trials generally exclude patients with comorbidities and current treatment guidelines do not specifically consider comorbidities, so treatment decisions are usually made on subjective individual-case basis.

Methods

Impacts of surgery, radiation, and chemotherapy mono-treatment as well as combined chemo/radiation on one-year overall survival (compared to no-treatment) are studied for stage-specific lung cancer in 65+ y.o. patients. Methods of causal inference such as propensity score with inverse probability weighting (IPW) for time-independent and marginal structural model (MSM) for time-dependent treatments are applied to SEER-Medicare data considering the presence of comorbid diseases.

Results

122,822 patients with stage I (26.8%), II (4.5%), IIIa (11.5%), IIIb (19.9%), and IV (37.4%) lung cancer were selected. Younger age, smaller tumor size, and fewer baseline comorbidities predict better survival. Impacts of radio- and chemotherapy increased and impact of surgery decreased with more advanced cancer stages. The effects of all therapies became weaker after adjustment for selection bias, however, the changes in the effects were minor likely due to the weak selection bias or incompleteness of the list of predictors that impacted treatment choice. MSM provides more realistic estimates of treatment effects than the IPW approach for time-independent treatment.

Conclusions

Causal inference methods provide substantive results on treatment choice and survival of older lung cancer patients with realistic expectations of potential benefits of specific treatments. Applications of these models to specific subsets of patients can aid in the development of practical guidelines that help optimize lung cancer treatment based on individual patient characteristics.

Impact of cigarette smoking on outcome of hepatocellular carcinoma after surgery in patients with hepatitis B

BACKGROUND AND OBJECTIVES

Cigarette smoking is a potential risk factor for hepatocellular carcinoma (HCC) initiation, partially through interaction with hepatitis B virus (HBV). We examined the hypothesis that cigarette smoking might be associated with HBV-related HCC recurrence and patient survival after curative surgery.

PATIENTS AND METHODS

Data of 302 patients with HBV infection who had undergone curative resection for HCC were prospectively collected from 2008 to 2011. Smoking status and smoking quantity (pack-years, PY) were asked at admission. Factors affecting recurrence-free survival (RFS) were examined. RFS and liver-specific mortality (LSM) stratified by risk factors were compared with log-rank test.

RESULTS

109 were current smokers. Current smokers were not different from non-smokers in tumor burden and surgical procedure. Univariate and multivariate analysis identified that heavy smoking (PY ≥ 20) was the most significant factor associated with HBV-related HCC recurrence after curative surgical resection (p = 0.001), followed by anti-HBV treatment (p<0.01), current smoking (p = 0.028), surgical margin <1 cm (p = 0.048) and blood transfusion >600 ml (p = 0.028). The median RFS in non-smokers, ex-smokers and current smokers was 34 months, 24 months and 26 months, respectively (p = 0.033). Current smokers had significantly worse RFS rate and increased 5-year cumulative LSM than non-smokers (p = 0.024, and p<0.001, respectively). Heavy smokers had significantly worse RFS than non- and light smokers (0

CONCLUSIONS

Smoking history and quantity appears to be risk factors for HBV-related HCC recurrence and LSM of patients after surgery. For smokers, continued smoking postoperatively might accelerate tumor recurrence and patient death. Therefore, smoking abstinence should be strongly recommended to patients pre- and postoperatively.

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MESH Headings

• Carcinoma, Hepatocellular/complications
• Carcinoma, Hepatocellular/physiopathology
• Carcinoma, Hepatocellular/surgery
• Female
• Hepatitis B/complications
• Humans
• Liver Neoplasms/complications
• Liver Neoplasms/physiopathology
• Liver Neoplasms/surgery
• Male
• Middle Aged
• Prognosis
• Recurrence
• Smoking/physiopathology
• Nicotiana

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Affiliation(s)

Xu-Feng Zhang Department of Hepatobiliary Surgery, the First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, China
Tao Wei Department of Hepatobiliary Surgery, the First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, China
Xue-Min Liu Department of Hepatobiliary Surgery, the First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, China
Chang Liu Department of Hepatobiliary Surgery, the First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, China
Yi Lv Department of Hepatobiliary Surgery, the First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, China

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The prognostic impact of cigarette smoking on patients with non-small cell lung cancer

INTRODUCTION

The purposes of this study are to investigate the association between cigarette smoking and clinicopathological characteristics of patients with non-small cell lung cancer (NSCLC) and to evaluate its significance as a predictor of recurrence after resection.

METHODS

A total of 2295 consecutive patients with NSCLC underwent complete resection with systematic node dissection between August 1992 and December 2006 at the National Cancer Center Hospital East.

RESULTS

A statistically significant difference in the 5-year overall survival rate was observed between never and ever smokers in patients with stage I (92% and 76%, respectively, p < 0.001) NSCLC, whereas no difference was observed in stage II (57% and 52%, respectively, p = 0.739) and stage III (30% and 33%, respectively, p = 0.897). In patients with stage I NSCLC, 5-year recurrence-free proportions (RFPs) for never and ever smokers were 89% and 80%, respectively (p < 0.001). In contrast, the 5-year RFPs for never smokers were lower than those for ever smokers in stage II (44% and 60%, respectively, p = 0.049) and stage III (17% and 31%, respectively, p = 0.004). In stage I patients, significant difference in 5-year RFP was observed between never and ever smokers (89% and 83%, respectively) in patients with adenocarcinoma, but not in patients with nonadenocarcinoma (82% and 76%, respectively).

CONCLUSIONS

Smoking history showed different impact on postoperative recurrence in patients with NSCLC between stage I and stages II and III, and depending on histology in stage I patients. Disease stages should be considered while evaluating smoking history as a predictor of recurrence.

Prognostic impact of histology on early-stage non-small cell lung cancer

BACKGROUND

The purpose of this study is to evaluate the significance of histology as a predictor of recurrence after resection in patients with early-stage non-small cell lung cancer.

METHODS

A total of 1,870 consecutive patients in stage I and II with adenocarcinoma or squamous cell carcinoma (SCC) who underwent complete tumor resection with systematic lymph node dissection between August 1992 and December 2007 were included.

RESULTS

In patients with SCC, significantly more tumors were stage IB or higher. Ever smokers were more common in patients with SCC, and more patients with SCC died of other diseases. In stage IA, a statistically significant difference in the 5-year recurrence-free probability was observed between adenocarcinoma and SCC (91.4% and 82.6%, respectively; P < .001), whereas no such difference was observed in stage IB (74.4% and 73.6%, respectively; P = .934). In stage II, the 5-year recurrence-free probability for adenocarcinoma was significantly lower than that for SCC (47% and 73%, respectively; P < .001). In stage IA, patients with predominantly bronchioloalveolar carcinoma subtype were more common compared with stage IB or higher in patients with adenocarcinoma.

CONCLUSIONS

It is important to offset the prognostic impact of comorbidities associated with cigarette smoking because more patients with SCC died of other diseases. When evaluating its significance as a predictor of recurrence stratified by stage, histology showed a different impact on postoperative recurrence within different substages. Histologic subtype distribution was different among substages in patients with adenocarcinoma. Disease stages should be considered while evaluating histology as a predictor of recurrence.

Long-term survival outcomes by smoking status in surgical and nonsurgical patients with non-small cell lung cancer: comparing never smokers and current smokers

BACKGROUND

Survival outcomes of never smokers with non-small cell lung cancer (NSCLC) who undergo surgery are poorly characterized. This investigation compared surgical outcomes of never and current smokers with NSCLC.

METHODS

This investigation was a single-institution retrospective study of never and current smokers with NSCLC from 1975 to 2004. From an analytic cohort of 4,546 patients with NSCLC, we identified 724 never smokers and 3,822 current smokers. Overall, 1,142 patients underwent surgery with curative intent. For survival analysis by smoking status, hazard ratios (HRs) were estimated using Cox proportional hazard modeling and then further adjusted by other covariates.

RESULTS

Never smokers were significantly more likely than current smokers to be women (P < .01), older (P < .01), and to have adenocarcinoma (P < .01) and bronchioloalveolar carcinoma (P < .01). No statistically significant differences existed in stage distribution at presentation for the analytic cohort (P = .35) or for the subgroup undergoing surgery (P = .24). The strongest risk factors of mortality among patients with NSCLC who underwent surgery were advanced stage (adjusted hazard ratio, 3.43; 95% CI, 2.32-5.07; P < .01) and elevated American Society of Anesthesiologists classification (adjusted hazard ratio, 2.18; 95% CI, 1.40-3.40; P < .01). The minor trend toward an elevated risk of death on univariate analysis for current vs never smokers in the surgically treated group (hazard ratio, 1.20; 95% CI, 0.98-1.46; P = .07) was completely eliminated when the model was adjusted for covariates (P = .97).

CONCLUSIONS

Our findings suggest that smoking status at time of lung cancer diagnosis has little impact on the long-term survival of patients with NSCLC, especially after curative surgery. Despite different etiologies between lung cancer in never and current smokers the prognosis is equally dismal.

Activation of both nuclear factor of activated T cells and inhibitor of nuclear factor-kappa B kinase beta-subunit-/nuclear factor-kappa B is critical for cyclooxygenase-2 induction by benzo[a]pyrene in human bronchial epithelial cells

The carcinogenic effect of benzo[a]pyrene (B[a]P), presenting mainly in cigarette smoke and air pollution, has been well demonstrated both in vitro and in vivo. However, it is still not well understood how B[a]P facilitates pulmonary carcinogenesis. To explore this, we investigated the effect of B[a]P on the induction of cyclooxygenase-2 (COX-2), a critical enzyme implicated in inflammation and cancer development, as well as upstream signaling pathways leading to its expression in human bronchial epithelial cells (Beas-2B). We found that exposure of Beas-2B to B[a]P caused significant COX-2 induction at both the transcriptional and protein levels. B[a]P also switched on the nuclear factor of activated T cells (NFAT) and nuclear factor kappaB (NF-kappaB) signaling pathways. B[a]P-induced COX-2 expression was significantly blocked by inhibition of the NFAT pathway, and impairment of the NF-kappaB signaling pathway by ectopic expression of an inhibitor of nuclear factor-kappaB kinase beta-subunit (IKKbeta) kinase inactive mutant (IKKbeta-KM) also dramatically inhibited COX-2 induction. The IKKbeta/NF-kappaB-dependent COX-2 induction was further confirmed in mouse embryonic fibroblasts with IKKbeta deficiency (IKKbeta(-/-)) and in those that expressed reconstituted IKKbeta. However, activation of the NFAT and NF-kappaB signaling pathways by B[a]P were independent of each other, as blocking one signaling pathway didn't interrupt the activation of the other one. Mutation of either NFAT or NF-kappaB binding sites significantly blocked COX-2 promoter induction by B[a]P. Taken together, these data indicate that exposure of Beas-2B to B[a]P can upregulate COX-2 expression by increasing its transcription, which requires activation of both the NFAT and NF-kappaB signaling pathways.

Treating tobacco dependence: review of the best and latest treatment options

Globally, an estimated 85% of lung cancer in men and 47% of lung cancer in women is attributable to tobacco smoking. Tobacco dependence treatment remains the most cost-effective way to prevent morbidity and mortality from lung cancer. Several effective pharmacotherapies are available to treat tobacco dependence. However, the long-term effectiveness of these treatments has been limited because the majority of smokers who attempt to stop smoking eventually relapse. Approaching the treatment of tobacco use and dependence as a chronic disease and the development of innovative drug therapies offer new hope for the treatment of tobacco-dependent patients. The diagnosis of lung cancer provides a teachable moment to motivate patients to attempt tobacco abstinence on which clinicians should capitalize. We review the currently available pharmacologic approaches to the treatment of tobacco dependence.

Smoking cessation before diagnosis and survival in early stage non-small cell lung cancer patients

Smoking cessation decreases the risk of lung cancer. However, little is known about how smoking cessation affects lung cancer survival. We examined the association between smoking cessation and overall survival (OS) and recurrence-free survival (RFS) in 543 early stage non-small cell lung cancer (NSCLC) patients. The data were analyzed using log-rank test and Cox proportional hazard models, adjusting for age, gender, stage, and smoking intensity. The median follow-up time was 57 months (range 0.2-140 months). There were 191 recurrences and 285 deaths. The 5-year OS rates were 50% (95% confidence interval (CI), 43-58%) for current smokers, 54% (44-65%) for ex-smokers who quit 1-8 years, 59% (49-70%) for ex-smokers who quit 9-17 years, 58% (47-69%) for ex-smokers who quit > or =18 years prior to diagnosis, and 76% (63-90%) for never smokers (P=0.09, log-rank test). The adjusted hazard ratios for ex-smokers who quit 1-8, 9-17, > or =18 years, and never smokers were 0.82 (95% CI, 0.59-1.13), 0.69 (0.49-0.97), 0.66 (0.45-0.95), and 0.54 (0.29-0.996), respectively, when compared with current smokers (P(trend)=0.004). Similar associations were found among ever smokers-only, when smoking cessation time was treated as a continuous variable, and for RFS. The significantly beneficial effects of smoking cessation on OS and RFS were observed among women only, while not among men (P=0.01 for interactions between gender and smoking cessation). In conclusion, smoking cessation is associated with improved survival in early stage NSCLC patients. The longer the time since cessation of smoking, the better the survival outcome.

Prognostic value of smoking status in operated non-small cell lung cancer

Despite the indisputable link between smoking and the increased risk for lung cancer, the inclusion of this factor in prognostic survival analysis has been scarce. Important clinical questions regarding the smoking status are the basis of this study and are as follow: what is the prognostic benefit of having been a non-smoker or having stopped smoking prior to developing lung cancer and what is the prognostic benefit of smoking cessation at the time of diagnosis of lung cancer? Cigarette smoking status of 311 patients operated for non-small cell lung cancer (NSCLC) by a single surgeon was determined based on two independent questionnaires taken prospectively prior to lung operation. Of all patients analysed, 169 (54.3%) were current smokers, 25 (8.0%) were non-smokers, 82 (26.4%) were former smokers and 35 (11.3%) were recent quitters. A Cox multiple regression model was used to test the prognostic value of smoking status on survival together with other relevant clinicopathological factors. For overall survival, older age (P = 0.011), presence of lymph node metastases (P < 0.001) and current smoking (P = 0.001) were independent predictors of poor prognosis, while non-smokers (relative risk = 0.447, 95% confidence interval = 0.206-0.970, P = 0.042), former smokers (relative risk = 0.543, 95% confidence interval = 0.350-0.843, P = 0.006) and recent quitters (relative risk = 0.340, 95% confidence interval = 0.164-0.705, P = 0.004) had a significant better prognosis compared to current smokers (referent group). Similar results were obtained for disease-free survival. These results indicate that smoking cessation is beneficial for lung cancer patients at any time point prior to lung operation and current smoking at the time of operation is associated with poor prognosis.

Smoking history before surgery and prognosis in patients with stage IA non-small-cell lung cancer—a multicenter study

The prognosis of lung cancer patients with surgically resected non-small-cell lung cancer (NSCLC) can be predicted generally from age, sex, histologic type, stage at diagnosis, and additional treatment. Nine studies have reported that a history of smoking before diagnosis influences the prognosis of the disease in lung cancer patients. In this study, a total of 3082 patients who underwent surgery and were diagnosed with primary pathological stage IA NSCLC at 36 national hospitals from 1982 to 1997 were analyzed for the effect of smoking on survival. Smoking history and other factors influencing either the overall survival or the disease-specific survival rates of patients were estimated with the Cox proportional hazards model. Multivariate analysis demonstrated significant associations between overall survival and age (P < 0.0001), sex (P = 0.0002), and performance status (PS) (P < 0.0001). Disease-specific survival was associated with age (P = 0.0063), sex (0.00161), and PS (P = 0.0029). In males, disease-specific survival was associated with age (P = 0.0120), PS (P = 0.0022), and pack-years (number of cigarette packs per day, and years of smoking) (P = 0.0463). These results indicate that smoking history (pack-years) is important clinical prognostic factor in estimating disease-specific survival, in male patients with stage IA primary NSCLC that has been surgically resected.

Duration of smoking abstinence as a predictor for non-small-cell lung cancer survival in women

BACKGROUND

Previous studies have attempted to investigate the impact of smoking cessation on lung cancer survival but have been limited by small numbers of former smokers and incomplete data.

METHODS

Over a six-year period, 5229 patients with non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) were enrolled in a prospective cohort of whom 2052 were former smokers. Patient's characteristics were obtained from medical records and a baseline interview. Vital status was determined through multiple sources. Cox proportional hazards models were used to estimate the effect of smoking abstinence on post-diagnosis mortality.

RESULTS

For all patients with NSCLC, the median survival among never, former, and current smokers was 1.4 years, 1.3 years, and 1.1 years, respectively (P < 0.01). Female NSCLC patients had a significantly lower risk of mortality with a longer duration of smoking abstinence (RR per 10 years of smoking abstinence = 0.85; 95% CI: 0.75, 0.97). No effect of smoking abstinence on mortality was observed for women with SCLC or for men with either histologic group.

CONCLUSIONS

The identification of smoking history as a prognostic factor in lung cancer survival supports previous research suggesting a direct biologic effect of smoking on survival. However, this effect may vary by sex and type of lung cancer.

CYP2E1 Polymorphism, Cigarette Smoking, p53 Expression, and Survival in Non-small Cell Lung Cancer

The expression of selected gene products involved in cell differentiation and cell growth and genetic polymorphism of detoxifying genes was examined in 105 surgically resected nonsmall cell lung cancer (NSCLC) patients, and the relationship of these factors was correlated with cigarette smoking and patient survival. Genotyping of peripheral blood lymphocytes from 87 patients was performed for CYP2E1, GSTM1, GSTT1, mEH, and MPO detoxifying genes using polymerase chain reaction. Formalin-fixed, paraffin-embedded tissue was immunostained with antibodies to p53, p27, phospho-AKT, and bcl-2 using the avidin-biotin-peroxidase method and tissue microarray technique. Tumors were assigned a positive or negative score based on more than 10% of tumor cells staining positive with the antibody. The subtypes of NSCLC included 48 adenocarcinomas, 47 squamous cell carcinomas, and 10 large cell undifferentiated carcinomas. A total of 54 tumors were pathologic stage I, 23 were stage II, and 26 were stage III. All subjects smoked (range, 10-175 pack-years; mean, 60 pack-years). The mean overall survival was 112 weeks (median, 129 weeks). Patients with p53-positive tumors had significantly fewer pack-years of smoking (52 pack-years vs 72 pack-years; P = 0.021), smoked fewer years (34 years vs 40 years; P = 0.018), and had significantly better survival compared with those with p53-negative tumors (P = 0.045). When smoking history was further analyzed, the authors found that p53 expression was associated with the number of years smoked and not the number of packs smoked per day. Patients with squamous cell carcinoma had smoked longer compared with those with adenocarcinoma (P = 0.011). Significant association was seen between the CYP2E1 wild-type allele and better survival (P = 0.016). Patients with stage I tumors had better survival compared with stages II and III (P = 0.032). No association was found between survival and tumor type; tumor differentiation; expression of phospho-AKT, p27, and bcl-2; and polymorphic metabolizing genes other than CYP2E1. The significant association of long duration of smoking (>40 years) with loss of p53 expression and poor survival suggests inactivation of the protective p53 pathway in those who had a history of more than 40 years of smoking.

Paradoxes of Non-Trivial Gene Networks: How Cancer-Causing Mutations Can Appear to Be Cancer-Protective

Abnormalities of gene structure or expression are commonly found in cancers, where they are used as prognostic markers, predicting the likely severity of disease or chances of response to therapy. An odds ratio (OR) of <1 indicates that a marker's presence is correlated with better outcome. An OR of <1 is also often taken to mean that the gene concerned has a protective effect in the mechanism of cancer. I show that this is not necessarily so. Modeling of the genes involved in the causation of cancer as a network of weak, failure-prone elements shows that "cancer-causing" genes (i.e., genes whose abnormality is causal in driving cancer) can nevertheless appear as "protective" markers in later stage cancers. This implies that results suggesting that well-known oncogenes have an OR of <1 are quite valid, and that predicting a "protective" role from an apparently protective prognostic value is not valid. I identify mdm-2 and bax as candidates for genes with an apparently protective role through this mechanism.

Clinical value of p53, c-erbB-2, CEA and CA125 regarding relapse, metastasis and death in resectable non-small cell lung cancer

The prognostic value of p53 and c-erbB-2 immunostaining and preoperative serum levels of CEA and CA125 was investigated in a prospective multicentric study including 465 consecutive non-small cell lung cancer (NSCLC) patients with resectable tumors. Four end-points were used: lung cancer death, first relapse (either locoregional or metastasis), loco-regional recurrence and metastasis development. Standard statistical survival methods (Kaplan-Meier and Cox regression) were used. The specificity of the prognostic effect across different types of tumors was also explored, as had been planned in advance. Our results showed, once again, that pathological T and N classifications continue to be the strongest predictors regarding either relapse or mortality. Three of the studied markers seemed to add further useful information, however, but in a more specific context. For example, increased CEA concentration defined a higher risk population among adenocarcinomas but not among people with squamous tumors; and p53 overexpression implied a worse prognosis mainly in patients with well differentiated tumors. The analysis of type of relapse proved to be very informative. Thus, CA125 level was associated with a worse prognosis mainly related with metastasis development. Another interesting result was the influence of smoking, which showed a clear dose-response relationship with the probability of metastasis. For future studies, we recommend the inclusion of different endpoints, namely considering the relationship of markers with the type of relapse involved in lung-cancer recurrence. They can add useful information regarding the complex nature of prognosis.

Smoking and Lung Cancer Survival

STUDY OBJECTIVE

Numerous studies indicate that smoking is associated with poorer outcomes in patients with cancer. The aim of this study was to determine whether smoking independently predicts survival in patients with lung cancer or whether an existent effect is mediated through comorbidity and/or treatment.

DESIGN AND SETTING

Cox proportional hazards analysis was used to study a cohort of 1,155 patients with lung cancer diagnosed at the Henry Ford Health System between 1995 and 1998, inclusive.

RESULTS

Adjusted for the baseline covariates, age, gender, illicit drug use, adverse symptoms, histology, and stage, the hazard ratio (HR) for smoking (current vs former/never) was 1.37 (95% confidence interval [CI], 1.18 to 1.59; p < 0.001). Adjusted for the baseline covariates and for 18 deleterious comorbidities, the HR for smoking was 1.38 (95% CI, 1.18 to 1.60; p < 0.001), indicating that the hazardous effect of smoking was not mediated through comorbidity. Current smoking was inversely associated with treatment (any surgery and/or chemotherapy and/or radiation therapy vs none) [odds ratio, 0.73; 95% CI, 0.55 to 0.98 (p = 0.03)]. Adjusted for baseline covariates, comorbidities and treatment, the HR for current smoker vs former/never was 1.26 (95% CI, 1.08 to 1.47; p = 0.003), a decline of 30.7% explained by treatment (HR for any treatment vs none, 0.40; 95% CI, 0.33 to 0.48; p < 0.001).

CONCLUSIONS

Current smoking at diagnosis is an important independent predictor of shortened lung cancer survival. That this effect was not explained by sociodemographic/exposure factors, adverse symptoms, histology, stage, comorbidity, and treatment suggests that it may be mediated through direct biological effects.

Impact of comorbidity on lung cancer survival

Lung cancer is associated with smoking and age, both of which are associated with comorbidity. We evaluated the impact of comorbidity on lung cancer survival. Data on 56 comorbidities were abstracted from the records of a cohort of 1,155 patients. Survival effects were evaluated with Cox regression (outcome crude death). The adjusted R(2) statistic was used to compare the survival variation explained by predictive variables. No comorbidity was observed in 11.7% of patients, while 54.3% had 3 or more (mean 2.97) comorbidities. In multivariate analysis, 19 comorbidities were associated with survival: HIV/AIDS, tuberculosis, previous metastatic cancer, thyroid/glandular diseases, electrolyte imbalance, anemia, other blood diseases, dementia, neurologic disease, congestive heart failure, COPD, asthma, pulmonary fibrosis, liver disease, gastrointestinal bleeding, renal disease, connective tissue disease, osteoporosis and peripheral vascular disease. Only the latter was protective. Some of the hazards of comorbidities were explained by more directly acting comorbidities and/or receipt of treatment. Stage explained 25.4% of the survival variation. In addition to stage, the 19 comorbidities explained 6.1%, treatments 9.2%, age 3.7% and histology 1.3%. Thirteen uncommon comorbidities (prevalence <6%) affected 21.2% of patients and explained 3.5% of the survival variation. Comorbidity count and the Charlson index were significant predictors but explained only 2.5% and 2.0% of the survival variation, respectively. Comorbidity has a major impact on survival in early- and late-stage disease, and even infrequent deleterious comorbidities are important collectively. Comorbidity count and the Charlson index failed to capture much information. Clinical practice and trials need to consider the effect of comorbidity in lung cancer patients.