Source: www.medpagetoday.com
Author: Charles Bankhead, Staff Writer, MedPage Today

Patients with newly diagnosed tonsillar cancer can have long-term disease control and minimal risk of contralateral recurrence with ipsilateral (same side) radiation therapy, data from a large patient series showed.

Only two of 102 patients had contralateral failure during a treatment experience dating back to 1970. Ipsilateral radiation therapy resulted in 100% locoregional control at the primary site and ipsilateral neck.

“In properly selected patients, ipsilateral radiotherapy to the involved primary site and neck provides excellent local control with a low risk of contralateral nodal failure,” Gregory Chronowski, MD, of M.D. Anderson Cancer Center in Houston, reported at the Multidisciplinary Head and Neck Cancer Symposium.

“High neck, nonbulky, N2b neck disease does not appear to be a contraindication to ipsilateral radiotherapy in patients with T1-T2 primary tumors. Neck dissection appears to offer reasonable salvage therapy in the event of isolated contralateral neck failure.”

Limiting radiation therapy to the ipsilateral primary site and neck offers potential advantages over more extensive irradiation. Limiting the treated area minimizes the risk of xerostomia and avoids complications related to exposure of the uninvolved contralateral vasculature, dentition, and musculature.

A retrospective review of a large case series from Toronto provided the first evidence that a limited approach to radiation therapy offers good local control and minimal risk of contralateral failure (Int J Radiat Oncol Biol Phys 2001; 51: 332-43).

That analysis showed a three-year local control rate of 77%, cause-specific survival of 76%, and contralateral failure rate of 3.5%.

To add to the information base, Chronowski and colleagues reviewed records on patients treated for squamous cell carcinoma of the tonsil at M.D. Anderson from 1970 to 2007. The identified 901 patients, 102 of whom received radiation therapy limited to the primary tumor site and the same side of the neck.

In general, ipsilateral treatment is reserved for a selected patient population. All patients in the series had stage TX-T2 disease and NX to N2b nodal status.

Cases of N2b disease were generally low volume and located high in the neck. The patients had minimal (≤1 cm) soft palate involvement and no involvement of the base of the tongue.

Chronowski said half of the patients had T1 disease and 33 had T2 disease. Nodal status was fairly evenly distributed across N0 to N2b.

In 60% of cases, patients had tonsillectomy before radiation therapy. Additionally, 26% underwent excision of the cervical lymph node or neck dissection before radiotherapy, and 18% underwent ipsilateral neck dissection after radiotherapy. Chronowski said 2% of patients had residual tumor.

The median follow-up among surviving patients was 3.2 years, including 86% of survivors followed for more than two years.

No patient had locoregional failure at the primary tumor site or ipsilateral neck.

The two contralateral failures consisted of one patient who had reappearance of cancer at the base of the tongue and neck four years after radiation therapy. The pattern suggested the possibility of a second primary, said Chronowski.

The second patient had an isolated contralateral neck failure less than a year after completing radiation therapy. Following contralateral neck dissection, the patient has remained with no evidence of disease.

Notes:
1. Primary source: Multidisciplinary Head and Neck Cancer Symposium
2. Source reference: Chronowski GM, et al “Ipsilateral radiation therapy for squaous cell carcinoma of the tonsil” MHNCS 2010; Abstract 9.