Head and Neck Radiation Oncology: Is Busier Better?
Authors: Sung Kim
Journal: Journal of Clinical Oncology (2016)

In recent years, head and neck radiation oncology has seen a pronounced shift away from treatment with three-dimensional conformal radiation therapy (3DCRT) to intensity-modulated radiation therapy (IMRT). 3DCRT typically means treating with three large radiation fields from the left, right, and anterior, whereas IMRT is a much more complicated technology that requires two to three times the number of fields and allows each pixel in individual fields to have a varying intensity. This allows for much more conformal treatment. Unlike 3DCRT, which treats with large, extensive fields, IMRTrequires the radiation oncologist to precisely delineate tumor versus normal tissues on every computed tomography slice, and so carries the possibility of missing tumor tissue. IMRT, however, can spare normal tissues, such as parotid glands, pharyngeal constrictor muscles, and other mucosal surfaces, which confers advantages in reducing toxicities, such as xerostomia, and swallowing dysfunction. In the article that accompanies this editorial, Boero et al ask whether provider volume, defined as the number of patients with head and neck cancer treated definitively per physician per year as ascertained using CPT codes, correlatedwith all-causemortality, head-andneck cancermortality, and toxicity end points. This was a retrospective study using the SEER Medicare database. Whereas the authors found no correlation between provider volume and survival for patients receiving non-IMRT (ie, 3DCRT techniques), they found that the risk of all-cause mortality for patients receiving IMRT decreased by 21% for every five additional patients treated by a provider per year. Like any retrospective study, the study by Boero et al has to be scrutinized for the possibility of selection bias. For example, did the healthier patients or those with more curable head and neck cancers tend to go to high-volume radiation oncologists? In general, the patients receiving IMRT who were treated by lowversus high-volume practitioners seemed well balanced but there were some statistically significant differences: patients treated by high-volume providers tended more often to be white, from the South, and less likely to receive cetuximab. Another potential bias is that perhaps it is not so much the volume of patients treated by the individual practitioner that made the difference, but the surroundings that accompany being in a high-volume center, such as better supportive care, more experienced ENT surgeons, multidisciplinary tumor boards, and better equipment. Arguing against this point of view, of course, is the fact that provider volume only made a difference in the more technically challenging technique (IMRT) but not in the less technically challenging technique (non-IMRT). There are already data to suggest that patients treated in clinical trials at historically low-accruing centers have worse overall survival compared with those treated at high-accruing centers. In addition, the Trans Tasman Radiation Oncology Group (TROG) reported that major radiation plan deficiencies correlated with the number of patients enrolled at the treatment center, and that these deficiencies translated to inferior overall survival in those patients taken to at least 60 Gy. Why these studies found that survival correlated with patient volume in the setting of 3DCRT treatment, whereas the current study does not, is not entirely clear. It is worth noting again, however, that the two aforementioned studies were different from the current study; they looked at institutions (not individuals) and used data from clinical trials (not SEER Medicare data). How should the study by Boero et al affect clinical care? These data suggest that perhaps patients with head and neck cancer may be better off seeking centers and practitioners who treat a high volume of patients with head and neck cancer. However, the study is not definitive, and this would seem to be a partial solution at best, as our medical system is simply not designed to funnel patients with cancer to regional centers. Although this might be an ideal solution for those patients who live near such centers and practitioners, the severe toxicity associated with head and neck radiation would only exacerbate time spent traveling for those patients who do not. How, then, do we ensure the quality of IMRT plans for practitioners who do not see a high volume of patients with head and neck cancer? The American Society for Radiation Oncology, the European Society for Radiotherapy and Oncology, and the Radiological Society of North America clearly recognize the need for practical, hands-on education in IMRT contouring and offer multiple courses at their annual meetings and provide online resources, such as contouring atlases. There is also the promise of improved autosegmentation technology that may someday automate much of the contouring process. In addition, cooperative group trials and recent publications demonstrate that remote quality review is technically feasible, although at the present time, the infrastructure to support electronic chart rounds is lacking for most centers. A logical but difficult question that arises from this study is should a practitioner who sees two or three patients with head and neck cancer a year even perform IMRT? After all, in the PARSPORT (Parotid-Gland Sparing IMRT in Patients With Midline Tumour of the Head and Neck) randomized controlled trial of IMRT versus conventional radiation, IMRT decreased xerostomia, but did not affect locoregional control. A radiation oncologist could opt to treat with large fields and accept the certainty of severe xerostomia, knowing that there is a decreased