The Combined Lung Cancer Register included 3,331 resident cases (1,050 Māori and 2,281 non-Māori) between 2011 and 2018. This study included 583/3,331 (17.5%) with early stage disease (Table 1). This was made up of 169/1,050 (16.1%) Māori and 414/2,281 (18.1%) non-Māori patients. Over 90% of the early stage patients were either a current smoker (30.9%) or ex-smoker (60.1%). Among the lung cancer patients, 47.7% had a history of chronic obstructive pulmonary disease (COPD). There were 452 cases of NSCLC, 14 cases of small cell lung cancer, and 106 patients did not have a pathology report. A record of unknown pathology was associated with significant comorbidities in 37 (34.9%) patients, frailty/high risk – ECOG 2+ 10 (9.4%) and very poor lung function 25 (23.6%). The 169 Māori patients were younger, more likely to be current smokers, have a diagnosis of COPD and have NSCLC-other and small cell lung cancer, and more likely to have FEV1 of <50% than non-Māori patients.
In total 419/583 (71.9%) of patients with Stage I and II disease were treated with curative intent - 272 (46.7%) patients had curative surgery, including 199 lobectomies, 59 partial resection of lung, and 14 pneumonectomy (Table 2). Another 64 (11.0%) patients were treated with SABR, 67 (11.5%) received curative radical radiotherapy, and 16 (2.7%) had curative chemo/radiotherapy. Amongst those not having curative treatment (164 (28.1%)), 33 (5.7%) had palliative radiotherapy, 14 (2.4%) had palliative chemotherapy, and 117 (20.1%) had best supportive care alone. Māori patients appeared to be less likely to have curative surgery (39.6% vs 49.5%, p-value=0.027), but were as likely to have curative treatment as non-Māori patients (70.4% vs 72.5%, p-value=0.618). The principal reason recorded in the patient records indicating why these lung cancer patients did not have curative treatment included significant comorbidities in 37 (22.6%) patients, 24 (14.6%) poor lung function, 24 (14.6%) poor ECOG status, 19 (11.6%) high risk of surgical complications, 16 (9.8%) patient refusal and 43 (26.2%) unrecorded.
The logistic regression model showed that age, year of diagnosis, cancer stage, cancer cell type, FEV1 and ECOG status had an impact on the likelihood of having curative treatment (Table 3). Patients who were younger, were diagnosed in more recent years, had stage I disease, had NSCLC, had FEV1 of 80%+, and had an ECOG score of 0 were more likely to receive curative treatment. Amongst those who received curative treatments, younger patients were more likely to have surgery as the primary treatment (odds ratio: 0.91, 95%:0.87-0.95). Current smokers and ex-smokers were less likely to have surgery and more likely to be treated with radiotherapy and chemotherapy than people who never smoked (respective odds ratio: 0.11 (95% Confidence interval (CI): 0.02-0.46); 0.23 (95% CI: 0.06-0.89)). Patients who had NSCLC, had FEV1 of 80%+, and had an ECOG score of 0 were more likely to undergo surgery. After adjustment for other factors we did not find a difference in access to curative treatment and curative surgery between Māori and non-Māori patients (respective odds ratio: 0.80 (95% CI: 0.46-1.38); 1.03 (95% CI: 0.53-2.00)).
There were 217 deaths (37.3%) in this cohort with a median follow-up time of 27 months and a mean follow-up time 34 months. Outcomes in patients with stage I and II lung cancer varied depending on the treatment received (Figure 1). Those who were treated with surgery had a 2-year survival of 87.8% (95% CI: 83.8%-91.8%) and 5-year survival of 69.6% (95% CI: 63.2%-76.0%). SABR has only been available in the region since mid 2015 but outcomes are similar to surgery in the first two years post treatment (2-year survival: 85.2%, 95% CI: 75.8%-94.7%, log-rank test p-value=0.556). Prior to the use of SABR, some patients were offered radiotherapy with curative intent and in this group of patients 2-year survival is only 65.3% (95% CI: 53.1%-77.4%) and 5-year survival was 50%. Patients offered palliative treatment only had a 2-year survival of 45.0% (95% CI: 37.0%-53.0%) and 5-year survival of 31.8% (95% CI: 23.9%-39.6%).
Māori patients had a similar survival to non-Māori patients (Figure 2, Log-rank test p-value=0.091). The 2-year and 5-year survival for Māori patients was 69.4% (95% CI: 62.2%-76.7%) and 47.1% (95% CI: 37.8%-56.4%), compared to 73.5% (95% CI: 69.1%-77.9%) and 59.3% (95% CI: 53.9%-64.8%) for non-Māori patients.
The hazard ratio (Table 4) of all-cause mortality for Māori patients compared to non-Māori patients was 1.25 (95% CI: 0.92-1.69, p-value=0.150). SABR has equivalent effect on survival compared to curative surgery (hazard ratio: 0.77, 95% CI: 0.37-1.61). The all-cause survival for stage I and II lung cancer patients has improved over time (hazard ratio: 0.94, 95% CI: 0.87-1.00).