RADIATION FILEDS IN NASOPHARYNGEAL CARCINOMA 

NEW YORK (Reuters Health) Jun 20 - Patients with node-negative nasopharyngeal carcinoma (NPC) don't need prophylactic node irradiation to the whole neck -- upper neck irradiation is sufficient, according to radiation oncologists from China.

In a randomized controlled trial they found similar overall, relapse-free, and metastasis-free survival rates among patients with node-negative NPC who received irradiation to the whole neck or just the upper neck.

"Based on our study, as well as several recent retrospective studies and one prospective phase II study, we think that patients with node-negative NPC should only be prophylactically irradiated to the upper neck nodal levels, if the patients were staged by modern imaging techniques, such as MRI or CT with or without PET-CT," lead author Jin-Gao Li, from Jiangxi Cancer Hospital in Nanchang, told Reuters Health by email.

"This is practice-changing," Dr. Li said.

But radiation oncologists at Memorial Sloan-Kettering Cancer Center in New York caution against jumping to conclusions based on this study, which was online June 13 in Cancer.

"To state that two treatments are equivalent, a large number of patients are needed," Dr. Nadeem Riaz and Dr. Nancy Lee told Reuters Health by email. "Given the size of this study, the authors were unable to rule out the possibility of a 2-fold increased risk of relapse between the arms even though there was no detectable difference between the two arms."

Between November 2005 and June 2012, Dr. Li and colleagues randomly assigned 301 patients with node-negative NPC to receive primary plus prophylactic upper-neck irradiation (UNI, 153 patients) or primary plus whole-neck irradiation (WNI, 148 patients).

Patients in both groups received radiation to the primary tumor and the upper-neck nodal regions, and patients in the WNI group also received radiation to the lower neck.

Patient characteristics were well balanced with respect to sex, age, staging, suspicious nodes and radiotherapy modality, and compliance with the protocol was good: 147 of 153 patients in the UNI group and 145 of 148 in the WNI group received the full dose of radiotherapy as per the study protocol.

With a median follow-up period of 39 months, no patient in either group had a cervical node relapse. At three years, the overall survival rate was 89.5% in the UNI group and 87.4% in the WNI group (hazard ratio, 0.866; p=0.70); the relapse-free survival rate was 89.8% and 89.3%, respectively (HR, 0.914; p=0.82); and the metastasis-free survival rate was 91.7% and 90.9% (HR 1.007, p=0.99).

No significant differences were seen in the overall toxicities between the two groups, but more than two-thirds of the patients in the WNI group had faint erythema during radiotherapy in the lower neck regions, and 13.5% of patients had grade I skin atrophy in the lower neck regions and 4.7% had fibrosis of the lung apex. All patients recovered completely.

"Our results confirmed the hypothesis that the probability of lower neck occult metastases by subclinical nodes was extremely low in patients who had node-negative NPC, and the omission of the lower neck during prophylactic node irradiation did not decrease the rate of lower neck control," Dr. Li and colleagues write in their paper.

They point out that the "exceptionally low" neck relapse rate in the study might be partly due to the 10-Gy boost delivered to the suspicious nodes, which could have improved the treatment of subclinical disease.

They conclude in their paper that "UNI is sufficient as prophylactic node irradiation for patients with N0 NPC."

But Drs. Riaz and Lee disagree. "Although the authors found no difference in outcome by omitting radiotherapy to the lower neck, they also did not notice any significant improvement in quality of life or toxicity of patients who did not receive treatment."

"We still favor treating the lower neck in all nasopharyngeal cancer patients until there is additional prospective data suggesting equivalence focusing on efficacy since the side-effects from including this area are minimal and we know nasopharyngeal cancer has a propensity to spread through the lymphatics. Furthermore, the authors incorrectly stated that nodal spread is in an orderly pattern as there is data skip metastasis occurs up to 8% in nasopharyngeal carcinoma," Dr. Riaz and Dr. Lee told Reuters Health.

The study was supported by the Scientific Research Fund of the Health Administration of Jiangxi Province.

SOURCE: http://bit.ly/104C7rV

Cancer 2013.