Researchers are proposing a new tumor-staging model for predicting the outcomes and guiding treatments for patients with human papillomavirus (HPV)-related oropharyngeal cancer (OPC), according to a new study in the Journal of Clinical Oncology. Since HPV-related cancer differs significantly from smoking-related cancer, less intensive treatment strategies may be more appropriate, the study authors concluded.
Treatment regimens for oropharyngeal cancer have intensified over time and carry a toxicity burden, the Canadian researchers noted.
In the last few years, research has found that oropharyngeal cancer caused by HPV behaves differently than OPC caused by smoking and alcohol, yet both cancers use the same tumor classification model. Therefore, regardless of whether the OPC was caused by HPV or smoking, the treatment and perceived prognosis based on tumor staging has remained the same, even though patient outcomes vary considerably, the study authors noted (Journal of Clinical Oncology, February 10, 2015, Vol. 31:5, pp. 543-550).
A new tumor-staging model will help separate patients with promising prognoses from those with negative ones to design the most appropriate treatment strategies for each group, according to the researchers from Toronto's Princess Margaret Cancer Centre.
"This is the future of tumor staging," researcher Sophie Huang, MSc, said in a statement. Dr. Huang is an assistant professor in the department of radiation oncology at the University of Toronto. "We need to consider the patient as a whole. Both individual factors, how extensive the disease is in the patient, and tumor biology should play a role in determining the best course of treatment."
The researchers analyzed 899 oropharyngeal cancer patients, including 505 (56%) patients with HPV who had been treated with radiotherapy or chemoradiotherapy from 2001 to 2009. The HPV-positive patients (382) had higher recurrence-free survival rates after about four years compared with HPV-negative patients (123). Disease recurrence was 16.7% (64) among HPV-positive patients; 38.2% among HPV-negative patients (47).
The tumor staging system classifies the disease into early, intermediate, or advanced stages of cancer. It helps determine treatment plans and can suggest likely outcomes.
For example, a stage IV patient with HPV-related cancer has an 80% survival rate, while a stage IV patient with smoking-related cancer has a 50% to 60% survival rate. But both are currently considered to have advanced-stage disease, which is recognized as a life-threatening prognosis.
"When you tell a patient they have stage IV cancer, it's an indication of advanced disease, and they don't expect it to be curable," Huang said in a statement. "We need a staging system that more accurately reflects a patient's prognosis, which in a case caused by HPV is highly curable."
The study also highlights the fact that many HPV-related OPC patients are overtreated because of the stage IV tumor classification. High-dose chemotherapy combined with high-dose radiation is often given to such patients when radiation therapy alone or other less-intensive strategies can probably cure many of them, the researchers said.
"Our study shows that the current model derived for smoking- and alcohol-related cancers is not suited for throat cancer caused by HPV, a burgeoning throat cancer population in the Western world, including Canada," Huang concluded.
A new tumor staging model will help separate patients with promising prognoses from those with negative prognoses to design the most appropriate strategies for each group, the study authors concluded.
Clinical trials have now begun to address these questions, but their descriptions and designs are hindered by inadequacies of the current stage classification, they stated.
The study has several interesting characteristics besides the management of head and neck cancer, noted lead study scientist Brian O'Sullivan, MD, the lead researcher of the Head and Neck Site Group at the Princess Margaret Hospital at the University of Toronto.
"Providing a relevant stage classification for a rapidly emerging disease is important, but the additional feature of the classification is that it provides the opportunity to include factors beyond just the traditional description of disease extent into the prognostic classification we are trying to develop to assist in treating patients," he said.
The structure used for disease classification follows a template that was developed at the Union for International Cancer Control in Geneva and is relevant to all cancers, according to Dr. O'Sullivan.
"Important factors that are emerging throughout oncology are not currently included in the international classifications," he concluded. "This needs to change to facilitate our goal of providing personalized approaches to patients with cancer."
The Princess Margaret Hospital is collaborating with six major cancer centers worldwide to validate the findings.