There were 1,646 participants with stage IIIB or IV lung cancer; 1,371 remained after those with prior lung surgery or with missing sex or age data were excluded. Of these remaining patients, medical records indicated receipt of at least one course of chemotherapy for 798 (58%; 95% CI, 55% to 61%; ). Targeted molecular therapy was used by less than 3% of patients because of the time period of study. Almost half of patients received radiation therapy (); of these, 58% also received chemotherapy ().
Patients With Stages IIIb or IV NSCLC by Age Group in the CanCORS Study
Characteristics of Patients With Advanced Stage NSCLC Who Were Receiving Chemotherapy and Adjusted Probability of Receiving Chemotherapy in the CanCORS Study
Older adults were less likely to receive chemotherapy and to receive radiation therapy, had poorer respiratory function at diagnosis as measured by the ACE-27 respiratory indicator, and had more cardiovascular and other comorbidities at diagnosis (). Most patients (n = 864) were age 65 years or older, and 30% were age 75 years or older.
Age was strongly and inversely related to receipt of chemotherapy; after adjustment, 72% of patients younger than 55 years received chemotherapy, but only 47% of those age 75 years and older did (). Interview type, age, sex, histology, and degree of respiratory disease at diagnosis also were statistically significant predictors of the receipt of chemotherapy after analysis was adjusted. There were no significant interactions between age and any of the disease or comorbidity measures, which indicated that the inverse relationship between age and receipt of chemotherapy did not depend on these measures. Men were more likely than women to receive chemotherapy. To additionally explore this, we confirmed this association among the subset of participants for whom marital status was available (marital status was not collected in the brief version of the interview) and found that addition of marital status to the models eliminated the sex differences (data not shown). Those who were unable to complete the full baseline interview were less likely to receive chemotherapy.
We classified the first chemotherapy regimen for each patient as cisplatin based (n = 83; 10.4%), carboplatin based (n = 521; 65.3%), non–platinum based (n = 173; 21.6%), or unknown (n = 21; 2.6%). Most (n = 615; 79.2%) first chemotherapy regimens were multiagent regimens, and, of these, platinum-based regimens (n = 576) accounted for 93.7%. Most (n = 162) single-agent regimens were non-platinum agents. Among those treated with chemotherapy, older adults were less likely to receive a platinum-based first regimen; 84% (adjusted percent) of patients younger than 55 years were receiving a platinum-based treatment, and this decreased to 71% among patients age 75 and older (). Most of this difference was due to a lower rate of cisplatin use with advancing age (). After adjustment for all other variables, age, interview type, research site, and comorbidity were statistically significant predictors of the receipt of platinum-based chemotherapy ().
Characteristics of Patients With Advanced Stage NSCLC Receiving Chemotherapy Who Received Platinum-Based Regimens and Adjusted Probability of Receiving Platinum-Based Chemotherapy in the CanCORS Study
Older adults who received chemotherapy were less likely to have a clinically important acute medical event during the period from diagnosis to the start of chemotherapy than were younger adults, and this rate decreased from 18.6% among those younger than age 55 years to 9.2% among those age 75 years and older (). Although the CIs around the adjusted percents () overlap, adjusted rates that incorporated variable person-times were more precise, and the adjusted rate ratio for this difference was statistically significant (adjusted rate ratio, 0.49; 95% CI, 0.26 to 0.91).
Fig 1. Adjusted percent (and 95% CI) of patients with advanced non–small-cell lung cancer treated with chemotherapy (n = 798) who experienced medical events between diagnosis and treatment initiation by age on the CanCORS (Cancer Care Outcomes Research (more ...)
displays the frequency of the individual AEs recorded during chemotherapy use. The rates of adverse events among 702 participants who were event free before treatment are listed in . There were 365 events during 100,769 person-days of chemotherapy among 249 people (35%; 95% CI, 32% to 39%), so some had more than one type of AE during treatment. The highest AE incidence was among 65- to 74-year-olds (adjusted percent, 42.4%; 95% CI, 36.1% to 48.7%) for an adjusted rate ratio of 1.70 (95% CI, 1.19 to 2.43) when compared with those patients age younger than 55 years. Other variables that were related to AE rate after adjustment included interview type, research site, cardiovascular disease at diagnosis, and receipt of radiation (data not shown). There were no age interactions with any covariate, suggesting that AE rate for a given age group did not vary by levels of covariates (eg, cardiovascular and other comorbidity).
Types of Adverse Events Recorded Among Patients Who Received Chemotherapy in the CanCORS Study
Crude and Adjusted Rates of Adverse Events During Chemotherapy in the CanCORS Study
When AEs that were particularly likely to be chemotherapy-related were analyzed, the age relationship continued to be evident, and the highest rates were observed among those age 65 years and older (). Rate ratios for the individual chemotherapy-sensitive AEs followed the same age pattern but were individually of too low a frequency to be statistically significant. Other variables positively related to rate of the composite neuropathy/fever with neutropenia/sepsis measure after adjustment included inability to complete the full baseline interview, Los Angeles County and Iowa research sites, and greater percent of chemotherapy time spent on platinum.