Autonomic nervous system dysfunction in advanced cancer

Abstract

The autonomic nervous system (ANS) innervates every organ in the body and is largely involuntary. There have been reports of autonomic dysfunction in cancer patients, but most are case reports. There are suggestions that this abnormality may be common in advanced cancer. Inpatients and outpatients with advanced cancer were enrolled. Patients were excluded if they had a previous diagnosis of a disease associated with autonomic nervous system (ANS) abnormalities, or had taken or were taking drugs affecting the ANS. Autonomic function was evaluated using five bedside cardiovascular tests: (1) heart rate response to deep breathing, (2) heart rate response to standing, (3) heart rate response to the Valsalva maneuver, (4) blood pressure response to standing and (5) blood pressure response to static exercise. Each test result was scored according to a validated scale of 0,.5, or 1. The individual scores were added together and each patient received a dysfunction score: none (=0-1), mild (=1.5-2), moderate (=2.5-3) or severe (=3.5-5). Twenty-eight men and 22 women participated, median age was 64 years. The median ECOG performance status was 2. Lung and prostate cancer were the most common (N=9, 5). 245 tests were performed; 86 (35%) individual tests were normal or borderline. Composite dysfunction scores were calculated; all the participants had a score consistent with abnormality. The median number of symptoms was 6 (range 1-15). Twenty-eight rated at least one symptom as severe (median 2, range 0-5), but symptoms did not correlate with test abnormalities. The results reveal significant ANS dysfunction in advanced cancer. There are more invasive tests that may give more accurate descriptions of ANS abnormalities in this population. These tests may help define the lesion better than these simple bedside tests. Further research with sophisticated ANS testing is needed to clearly define this paraneoplastic syndrome.