The HPV detection was performed by a less specific test-quantitative polymerase chain reaction (PCR)-thereby necessitating the class I, II and III designation. In our research there are HPV-positive and HPV-negative cases; this is the critical designation, Dr. Gillison said.
Explore This IssueSeptember 2006
Dr. Sturgis noted that significant confounding by stage/treatment specifics, tumor location, and smoking status exists in most studies reporting HPV; this impacts prognosis and makes definitive conclusions regarding prognosis premature. A clinical pathologist does not usually check for HPV status and these tumors are not typically studied unless patients are part of a clinical trial or research study.
However, because many metastatic cancers involving the neck of unknown primary origin likely originate in the oropharynx, this may become another area of clinical utility of HPV testing.
Developing New Treatments
Right now, regardless of whether a person is HPV-positive or -negative, you still treat their oropharyngeal cancer the same way, said Dr. Sturgis.
Current treatments include radiation therapy, chemotherapy, surgery, or combinations of these based upon the stage of the tumor. The stages of oropharyngeal cancer span from Stage 0 to Stage IV, depending upon the size and location of the tumor (inside or outside of oropharynx or spread to lymph node and other tissues).
New treatments under development include various biologic therapies, such as vaccines, growth factor-receptor antagonists, cyclin-dependent kinase inhibitors, oncolytic viruses, and others, as well as photodynamic therapy. Vaccines, generally thought of as more prophylactic, are now being studied as a way to treat people with cancer by helping their immune system to recognize and attack the cancer cells.
We have a clinical trial open now of an HPV-16 therapeutic vaccine, said Dr. Gillison. Patients with a diagnosis of HPV-16 positive oropharyngeal cancer are eligible for vaccination after completing standard of care therapy. The vaccine is a naked DNA vaccine designed to augment the T-cell response to the virus. This trial is a phase I dose escalation and safety evaluation of four vaccinations administered over an 18-week period. Four out of a planned total of 16 patients have been enrolled.
A second therapeutic, peptide-based vaccine is also in clinical trial at the University of Maryland, said Duane A. Sewell, MD, Assistant Professor of Otorhinolaryngology-Head and Neck Surgery at the Veterans Affairs Medical Center in the University of Pennsylvania Health System in Philadelphia. In future trials, findings from the Yale study, indicating that the expression of the key HPV-related genes such as p16 affects prognosis in these patients, will have to be taken into account. Patients will be screened not only for HPV subtype, but also for p16, p53, and retinoblastoma expression.
Vaccine May Reduce Oropharyngeal Cancer Incidence
Meanwhile, researchers are watching to see what happens with two prophylactic HPV vaccines for cervical cancers-one in the United States and one Europe-that are awaiting approval.