Such cancers are usually considered incurable, and the goal of treatment is generally limited to symptom control.
Sophie Huang, MSc, an assistant professor in the department of radiation oncology at the University of Toronto, presented research that shows certain patients with HPV+ OPC and distant metastases can survive for more than two years after intensive treatment without further evidence of disease.
Sophie Huang, MSc, assistant professor, Department of Radiation Oncology, University of Toronto. Image courtesy of the University of Toronto.
"Our research, the largest study to date to explore survival predictors for metastatic HPV+ and HPV- oropharyngeal cancer patients, has shown that cure is a realistic goal in those patients with oligometastasis -- metastases involving five or fewer lesions in one distant organ," Huang said in a press release.
The researchers identified 934 patients with HPV+ OPC out of the 1,238 OPC patients treated at Princess Margaret Cancer Centre between 2000 and 2011. Distant metastases were detected in 15% of these patients (88 in the HPV+ group and 54 in those with HPV- disease), while oligometastasis was present in 24 HPV+ patients with distant metastases in a single organ.
They found two types of distinct distant metastases in HPV+ patients: explosive and indolent. The explosive type of metastasis, where more than 10 lesions in one organ appear quickly in a short period of time (within three months of the first lesion), was present in 55% of the HPV+ group but in none of those who were negative for HPV.
In both the HPV+ and HPV- groups, the lungs were the most common metastatic site. The indolent metastasis type, which grows and spreads at a much slower pace and often manifests as oligometastasis, occurred in 24% of the HPV+ cases with metastases in a single organ, compared with 26% of those who had HPV- cancer.
"In the HPV+ group of patients with oligometastases, when they were given definitive local treatment aimed at disease control -- for example, a high radiation dose or surgical removal of the metastatic lesion, as opposed to a less aggressive treatment used to control symptoms -- there was a long-term disease-free period, suggesting that some may be cured," Huang said. "In the HPV+ group with oligometastases, 25% were still alive after three years, whereas the percentage in the HPV- group was 15%."
“Our research ... has shown that cure is a realistic goal in those patients with oligometastasis.”
— Sophie Huang, MSc, University of Toronto/Princess Margaret Cancer Centre
The researchers attributed the survival advantage for HPV+ OPC patients to a number of factors:
- The cancer is more sensitive to radiotherapy and chemotherapy.
- The patients tend to be younger (an average age of 55 at diagnosis, as opposed to 65).
- The patients have fewer health problems, including those caused by smoking-related illness.
These factors enable the patients to receive the more aggressive treatment.
"This research has shown that metastatic HPV+ OPC patients who receive active treatment can survive considerably longer than those who did not receive treatment," Huang said.
Physicians' perception plays an important role in a patient receiving aggressive treatment, she added.
"One of the reasons patients with metastatic disease do not receive aggressive treatment is due to the physician and patient's perception that this is an incurable state," she said.
She and her colleagues hope that these results will spur researchers to optimize management strategies that will produce a better quality of life for these patients, as well as lessen the cost to the healthcare system overall.
"Optimizing and tailoring surveillance strategies for HPV+ patients are also important," Huang noted. "For example, our research has shown that the surveillance period should be longer than the traditional two-year window, due to the possibility of later onset of metastases. Selecting the appropriate imaging method in order to detect asymptomatic oligometastasis may allow salvage treatment of some patients before the cancer progresses. Finally, we hope that it will help clinicians identify patients who are best able to benefit from aggressive treatment, such as metastasectomy or stereotactic radiotherapy."
Whether it's possible to identify which patients at initial presentation are at high risk of developing distant metastases and which type of metastases will develop are other important questions for future studies, according to the researchers.
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