Spinal Metastasis in Multiple Primary Malignancies Involving Lung Cancer: Clinical Characteristics and Survival

OBJECTIVE:The incidence of multiple primary malignancies (MPM) has increased in recent decades. Our aim was to evaluate incidence, clinical features, and survival in cases of spinal metastases from MPM in which one of the malignancies is lung cancer. METHODS:We retrospectively reviewed an institutional database of lung cancer patients with spinal metastasis and extracted all cases of MPM. RESULTS:Among 275 patients who had spinal metastasis with lung cancer as one of the diagnoses, 21 (7.6%) patients with MPM were identified. Mean patient age was 68.5 years (95% confidence interval [CI], 65.3-71.7). The most common cancers diagnosed in addition to lung cancer were breast cancer (5 patients, 24%), upper aerodigestive tract cancer (4 patients, 19%), and prostate cancer (4 patients, 19%). Eighteen (86%) patients walked independently, and 3 (14%) patients walked with help. Seventeen (80.9%) patients had a good Karnofsky performance scale score. The median survivals from the date of first cancer diagnosis, last cancer diagnosis, and spinal metastasis diagnosis were 109.8 months (95% CI, 23.5-196.1), 17.8 months (95% CI, 5.8-29.8), and 10.3 months (95% CI, 5.4-15.2), respectively. Actual rates of survival at 6 months, 12 months, and 24 months from the date of spinal metastasis diagnosis were 81%, 42.9%, and 23.8%, respectively. CONCLUSIONS:The present study is the first series to our knowledge to show that survival of patients with spinal metastasis and MPM involving lung cancer is not clearly inferior to that of patients with spinal metastasis and lung cancer alone.