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