HPV-positive squamous cell carcinoma of the oropharynx linked to later onset distant metastasis

Squamous cell carcinomas of the oropharynx (SCCOP) associated with human papillomavirus (HPV) usually have better outcomes that those not associated with HPV.  Patients with these cancers experience a later onset of distant metastasis and more metastatic sites in atypical locations, according to a new study by Samuel Trosman, MD and colleagues, of the Cleveland Clinic, Cleveland, Ohio. 

The study illustrated that even though the rates of distant metastasis is similar between patients with HPV-positive and HPV-negative SCCOP, distant metastases occur significantly later and involves more body sites. The researchers evaluated 285 patients with Stage III to IV SCCOP who were treated with chemo-radiation therapy between 2002 and 2013. Among the patients, 27 of 245 (11%) HPV-positive and 8 of 40 (20 %) HPV-negative patients developed distant metastases.

The radiation therapy regimen for the patients was either 3-dimensional radiotherapy or intensity modulated radiation therapy with doses from 66 to 79 Gy. Concurrent chemotherapy consisted of cisplatin, cisplatin/5-fluorouracil, or cetuximab.

Even though the distant metastasis rate between the HPV-positive and HPV-negative groups was similar, the mean time to develop the distant metastasis was significantly longer after the completion of treatment for HPV-positive patients (21.6 months) than for HPV-negative patients (7.0 months; P = .03).

The most common site of metastasis in both HPV-positive and negative individuals were the lung followed by bone. Patients who were HPV-positive had significantly higher average numbers of involvement in metastatic subsites compared with HPV-negative patients (2.0 vs 1.1; P = .026).

Among HPV-positive patients, 21 of 27 (78%) had  >1 metastatic site, and 12 (44%) had distant metastases involving >1 organ system, compared with only 1 of 8 (12.5%) HPV-negative patients. Spread to less typical metastatic sites occurred more often  in HPV-positive patients, and included liver (6), intra-abdominal lymph nodes (3), brain (2), pleura (2), and peritoneum (1). Local treatment failure occurred more often in HPV-negative patients (3 of 8  or 38%) compared to HPV-positive patients (4 of 27 or 15%).

 Sites of  oropharyngeal cancer caused by HPV