Comorbidity, age and overall survival in patients with advanced pancreatic cancer – Results from NCIC CTG PA.3: A phase III trial of gemcitabine plus erlotinib or placebo
Introduction
Pancreatic cancer is a significant problem worldwide. It ranks ninth versus seventh in incidence, and fourth versus fifth in cancer-related mortality in the United States1 and Europe,2 respectively. Despite efforts to improve therapeutic strategies, prognosis is dismal with a 5 year overall survival (OS) of 5.5%.3 Over the past decade, pancreatic cancer incidence has increased for both sexes and 53% of patients have metastatic disease at presentation.3 Primarily a disease of the elderly, the median age at diagnosis is 72 years and 68% of patients are ⩾65 years of age.3 With an aging population, pancreatic cancer incidence is expected to increase by 55% over the next 20 years.4
Despite their predominance among cancer patients generally, the elderly remain underrepresented in clinical trials.5, 6 Evidence suggests that patients aged ⩾65 years of age can benefit from experimental treatments and do not experience greater treatment-related mortality.5, 6 Though information is limited regarding the benefit and tolerance of chemotherapy in elderly patients with pancreatic cancer, small retrospective studies suggest that the elderly derive benefit from gemcitabine and do not experience greater toxicity.7, 8, 9 In addition to advanced age, the influence of comorbidity on treatment effects is poorly understood. Elderly patients have a higher incidence of comorbidities, yet elderly patients included in clinical trials are generally free of significant comorbidity and therefore may not be representative of the wider population with cancer.10
Although various methods exist to measure comorbidity in cancer patients, the Charlson Comorbidity Index (CCI) is the most widely recognised and has been shown to have prognostic value in breast, head and neck, prostate, lung and colorectal cancers.11, 12, 13, 14, 15 The index includes 19 medical conditions with weighted scores (1–6), which is based on the relative risk of death within 12 months. The total comorbidity score is represented by the sum of these weighted scores.14 In pancreatic cancer, there has been little investigation into the interaction between comorbidity and outcome in patients receiving chemotherapy. Aside from the association between performance status (PS) and outcome, little is known about prognostic factors in advanced pancreatic cancer.16, 17, 18, 19, 20
The independent ability of age, comorbidity and PS to predict outcome in pancreatic cancer is poorly understood, but of clinical importance. Herein we explore this relationship in the NCIC Clinical Trials Group (NCIC CTG) PA.3 clinical trial.
Section snippets
Patients
Five hundred and sixty-nine patients with locally advanced or metastatic pancreatic adenocarcinoma were randomly assigned to receive gemcitabine plus either erlotinib or a matched placebo as previously described.21 Prior chemotherapy was not permitted, except for fluorouracil or gemcitabine given concurrently as a radiosensitiser with radiotherapy for local disease. Other eligibility included histologic or cytologic evidence of adenocarcinoma of the pancreas, measurable or evaluable disease,
Baseline age and comorbidity scoring
Of the 569 patients, 47% (N = 268) were aged ⩾65 years old and 36% (N = 202) had comorbidities (Table 1, Table 2). 31.1% had a CCI = 1 and 4.2% had a CCI = 2. Only one patient included in the analysis had a CCI > 2. The two physician reviewers differed in CCI scoring 51 patient charts and consensus scores were reached after review of these charts.
Baseline diabetes, metformin therapy, insulin therapy and statin therapy
Thirty percent (N = 175) of patients had a baseline diagnosis of diabetes mellitus, 26% (N = 46) were using metformin and 46% (N = 81) were using insulin therapy (
Discussion
Since the relationship between advancing age, PS and comorbidity has not been adequately investigated in advanced pancreatic cancer, we undertook a retrospective analysis of the NCIC CTG PA.3 clinical trial to determine the role played by each of these factors as predictors of outcome. Our analysis revealed that in the total patient population on this trial, PS and baseline pain intensity were significantly correlated with survival, while neither age nor comorbidity was an independent
Disclosure
Presented in part at the American Society of Clinical Oncology Annual Meeting, Chicago, IL, June 2010. This project was supported by funding through the CAMO/CIHR/Rx&D Research Fellowship Programme.
Conflict of interest statement
Michael Vickers, none; John Hilton, none; Wendy Parulekar, none; Chris O’Callaghan, none; Dongsheng Tu, none; Erin Powell, honoraria – Roche, Pfizer; Timothy Asmis, Consultant, Research funding, Honoraria – Roche; Derek Jonker, Consultant (unremunerated) – Roche; Malcolm Moore, Consultant – OSI Pharma.
References (37)
- et al.
Estimates of cancer incidence and mortality in Europe in 2008
Eur J Cancer
(2010) Measuring comorbidity in older cancer patients
Eur J Cancer
(2000)- et al.
A refined comorbidity measurement algorithm for claims-based studies of breast, prostate, colorectal, and lung cancer patients
Ann Epidemiol
(2007) Clinical assessment of elderly people with cancer
Lancet Oncol
(2005)- et al.
A new method of classifying prognostic comorbidity in longitudinal studies: development and validation
J Chronic Dis
(1987) - et al.
Prognostic factors in nonresectable pancreatic adenocarcinoma: a rationale to design therapeutic trials
Am J Gastroenterol
(1999) - et al.
Pain as a predictor of outcome in patients with operable pancreatic carcinoma
Surgery
(1997) - et al.
Comorbidity and colorectal cancer according to subsite and stage: a population-based study
Eur J Cancer
(2000) - et al.
Sociodemographics and comorbidities influence decisions to undergo pancreatic resection for neoplastic lesions
J Gastrointest Surg
(2010) - et al.
Role of chemotherapy in the very elderly patients with metastatic pancreatic cancer – a veterans affairs cancer registry analysis
J Geriat Oncol
(2011)