Residual human papillomavirus DNA in plasma following chemoradiation for HPV-positive cervical cancer is not a good sign, investigators warn.
Among 19 women with HPV-positive cervical cancer who underwent definitive chemoradiation (CRT), detectable HPV DNA in plasma at the end of therapy was associated with a significantly lower rate of progression-free survival (PFS), reported, of the Princess Margaret Cancer Center in Toronto, and her colleagues.
“This prospective multicenter study shows that plasma HPV DNA is detectable at end of CRT in a subset of patients with locally advanced cervical cancer and is associated with poor PFS,” they wrote in.
The investigators also found that HPV DNA testing 3 months after the end of therapy is more accurate than 3-month fluorodeoxyglucose positron emission tomography (FDG-PET) for detecting minimal residual disease.
In a prospective study, the investigators enrolled 23 women with International Federation of Gynecology and Obstetrics stage IB to IVA cervical adenosquamous, adenocarcinoma, or squamous cell carcinoma who were scheduled to undergo CRT. Three of the patients had no detectable HPV DNA on pretreatment cervical swab, and were excluded from the study, and one patient did not complete therapy, leaving 19 patients with detectable plasma HPV DNA for the analysis.
Of these patients, six had detectable DNA at the end of treatment, and of this group, three had metastatic disease at 3 months. In contrast, only 1 of the 13 patients with no detectable DNA at the end of therapy had developed recurrent disease by the data cutoff.
Six of the 13 patients without detectable DNA at the end of treatment had positive 3-month FDG-PET results, but no definite residual disease on either subsequent imaging or clinical exam. Of these six patients, four had undetectable plasma HPV DNA at 3 months.
The accuracy of 3-month plasma HPV DNA for predicting relapse at 18 months was 77%, compared with 60% for 3-month FDG-PET (P = .008).
PFS at 24 months was significantly better for women with undetectable HPV DNA at the end of therapy, at 92% vs. 50% for women with detectable post-treatment HPV DNA (P = .02).
The authors acknowledged that the study was limited by the small sample size and by an 18-month PFS rate (79%) that was higher than expected, which reduced the statistical power to detect significant associations between HPV DNA and outcomes.
“Additional studies are warranted to confirm the prognostic significance of plasma HPV DNA after CRT and to test the clinical utility of plasma HPV DNA for guiding adjuvant/salvage therapy,” they concluded.
SOURCE: Han K et al. JCO Precis Oncol. 2018 Sep 13. .