Clinical features of metastatic cancer in primary care: a case-control study using medical records.

BACKGROUND How metastatic cancer initially presents is largely unknown. AIM To identify clinical features of metastatic cancer in primary care. DESIGN AND SETTING Case-control study in 11 general practices in Devon, UK. METHOD Cases of patients who had died with metastatic breast, colorectal, or prostate cancer were selected. In addition, two control groups were formed of patients with the same primary cancer but without metastases ('cancer controls') and patients without cancer ('healthy controls'), matched for age, sex, and practice. All symptoms, signs, and laboratory test abnormalities in the year before metastasis were identified. The primary analysis used conditional logistic regression. RESULTS In total, 162 cases, 152 cancer controls, and 145 healthy controls were studied. Common symptoms associated with cancer were: vomiting, 40 (25%) cases and 13 (9%) cancer controls (multivariable odds ratio [OR] 3.5, 95% confidence interval [CI] = 1.3 to 9.4, P = 0.011); low back pain, 38 (24%) cases and 17 (11%) cancer controls (OR 2.5, 95% CI = 1.1 to 5.6, P = 0.032); loss of appetite, 32 (20%) cases and nine (6%) cancer controls (OR 4.0, 95% CI = 1.2 to 13.2, P = 0.021); and shoulder pain, 27 (17%) cases and eight (5%) cancer controls (OR 5.3, 95% CI = 1.6 to 18, P = 0.007). Groin pain was uncommon, but strongly associated (16 [10%] cases and one [1%] cancer control [OR 10, 95% CI = 1.2 to 82, P = 0.032]), as was pleural disease (nine [6%] cases and one [1%] cancer control [OR 10, 95% CI = 1.1 to 92, P = 0.038]). CONCLUSION These features of disseminated cancer have been reported before in studies from secondary care, but the scarcity of specific symptoms (such as local pain) and the fairly common occurrence of non-specific symptoms (vomiting and loss of appetite) is important and may explain delays in the diagnosis of metastases.