The time may have come to talk about a cure for some cases of metastatic oropharyngeal cancer caused by human papillomavirus (HPV). This is a remarkable development, given the disease’s history of fatality. Sophie Huang, MRT(T), assistant professor in the Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, presented the details of a recent study at the International Conference on Innovative Approaches in Head and Neck Oncology in Nice, France, in her presentation “Cure” Is a Realistic Goal in HPV-Related Oropharyngeal Cancer With Oligometastasis. Huang and her group defined cure for their study as surviving 2 years or longer without evidence of disease. They note 10% of HPV-positive patients were cured, and are alive and disease-free for 2.0-7.7 years following treatment of their limited metastatic disease.1

The etiology of oropharyngeal cancer has changed. The disease used to affect older people who were predominantly smokers and alcohol users; however, it is now more likely due to HPV infection and afflicts a somewhat younger population. If identified and treated early, positive results can be achieved for these patients.

For this prospective study, Huang and her colleagues at the Princess Margaret Cancer Centre identified 142 patients with distant metastases (DM) in 1,238 consecutive patients with oropharyngeal cancer treated with definitive radiotherapy from 2000 to 2011. Of this group, 88 patients had cancer related to HPV, and 54 patients who were negative for HPV had cancer that was related to smoking. The researchers were searching for answers to how the metastases formed and how they affected the course of the disease, including survival.1 They found that, although rates of DM were similar between HPV-related and smoking-related oropharyngeal cancers, there were differences in terms of time to manifestation, characteristics, and natural course after treatment.

PACE OF MANIFESTATION

The time frame for detecting DM differed significantly between the groups. DM occurred in the HPV-negative patients quickly (94% within 2 years following initial radiation treatment), whereas DM occurred in 24% of HPV-positive patients beyond a 2-year time frame, with metastases detected the farthest, at 7.9 years. Huang said, “This observation indicates that HPV-related OPC patients who are disease-free for 2 years after initial treatment are not out of the woods. An important point of exploration is a longer surveillance period with appropriate detection methods to help identify DM earlier before widely disseminating, and to design optimal treatment for those with limited metastatic diseases. The hope is that this might cure HPV-positive patients with distant metastasis.”1

CHARACTERISTICS

The researchers reported two types of DM in HPV-positive patients. The types were identified by radiologic and histologic confirmation.

• Disseminating (to more than three organs), often with explosive manner defined as more than 10 lesions in one organ within a 3-month period following detection of DM.

• Oligometastasis defined as five or fewer indolent (slow growing) lesions in one organ.

Forty-seven patients in the HPV-positive group had DM in two or more organs, while there were 11 such cases in the HPV-negative group. Although 26 HPV-positive patients had explosive DM, none of the HPV-negative patients did. In both the HPV-positive and -negative patients, metastasis spread most often to the lung (78% vs 89%, respectively), although metastases can also be found in other unusual sites, such as the brain and intra-abdominal organs.1