The influence of comorbidities, age, and performance status on the prognosis and treatment of patients with metastatic carcinomas of unknown primary site - A population-based study

BACKGROUND. The authors investigated how comorbidities, age, and performance status were related to the choice of chemotherapy and to the prognosis of patients with carcinomas of unknown primary site (CUP). METHODS. Patients in Northern Alberta who were diagnosed with CUP during 2000 to 2003 were included (n = 389 patients). Survival was compared by age at diagnosis (ages < 65 years, 65-74 years, and > 75 years), comorbidity score (Adult Comorbidity Evaluation-27 [ACE-27] scores of 0-1 and > 2), performance status (PS), and other explanatory variables, such as gender, histology, and site and number of metastases. RESULTS. The median age was 68 years, and the median overall survival was 12 weeks. An ACE-27 overall comorbidity score > 2 was found in 34% of patients, and a PS > 2 was observed in 50% of patients. Multivariate analysis showed that patients who had a PS 2:2 and a high overall ACE-27 score had a worse prognosis. The impact of comorbidities on survival was limited to patients with low PS. Patients who were not evaluated at a cancer center were older, had a worse functional status, and had more moderate or severe comorbidities. Among the 257 patients who were evaluated at a cancer center, 108 patients received chemotherapy, and 121 patients had a good PS (0-1). Age was the only independent variable that was related to the likelihood of not receiving chemotherapy among patients who had a good PS. The median overall survival of the 121 patients who had a good PS was 317 days, and overall survival was not associated significantly with chemotherapy. A logistic regression analysis that included all patients who were evaluated at a cancer center identified young age, good PS, lymph node/pleural involvement, and few comorbidities as variables that were associated independently with receiving chemotherapy. CONCLUSIONS. Patients with CUP who were not evaluated at a cancer center were older, had a worse functional status, and had more moderate or severe comorbidities; this referral bias largely explained the differences between data from registries and from tertiary centers. Moderate and severe comorbidities impacted survival in patients with who had a PS >= 2. An age-related decline was observed in the percentage of adults with good PS who received chemotherapy. The current results suggested that older patients with CUP were under treated and that factors other than PS were involved in the decision to use chemotherapy for the treatment of patients with CUP.