Circulating antinuclear antibodies in patients with pelvic masses are associated with malignancy and decreased survival

Background

Circulating autoantibodies occur more frequently in cancer patients than in patients without cancer.

Methods and Findings

We examined sera from patients referred for pelvic mass symptoms to a tertiary university clinic. A total of 127 were diagnosed with epithelial ovarian cancer while 386 had a benign condition. A screen for IgG anti-nuclear antibodies (ANA) by indirect immunofluorescence on HEp-2 cells confirmed a highly significant overrepresentation of ANA in the cancer group where 40% had detectable (i.e., a titer ≥160) ANA compared with less than 12% in the benign group. The overrepresentation of ANA in the cancer group persisted (p<0.0001) after matching the age-profile of the benign group with the ovarian cancer group. Only 19 out of 127 patients in the age-matched benign subgroup were positive for ANA corresponding to an 85% specificity at 40% sensitivity of ANA as the only marker for malignancy. No correlation of ANA positivity in either group with specific bands in immunoblots could be demonstrated even though immunoblot positivity was clearly increased in the malignant group (41% vs. 3%). The presence, strength, and type of ANA did not correlate with serum CA-125 values or with staging, and ANA outcome did not contribute with independent diagnostic information. However, survival was significantly shorter in ANA-positive compared with ANA-negative cancer patients and patients with CA-125 below the median CA-125 value in the cancer group had a significantly decreased survival when positive for ANA. ANA status made no difference in the group with CA-125 values above the median. Also, there was a significant correlation between speckled ANA-strength and histological tumor grade.

Conclusions

Circulating antibodies are a promising source for new biomarkers in cancer. Characterization of epitope specificities and measurements of consecutive samples will be important for further elucidating the role of ANA in evaluating ovarian cancer patients.