Clinical investigation
Head and neck
Radiotherapy for solitary extramedullary plasmacytoma in the head-and-neck region: A dose greater than 45 Gy to the target volume improves the local control

Presented as a Poster Presentation at the Forty-Seventh Annual meeting of the American Society for Therapeutic Radiology and Oncology, October 16–20, 2005, Denver CO.
https://doi.org/10.1016/j.ijrobp.2005.09.019Get rights and content

Purpose: Our aim was to determine the dose to the clinical target volume (CTV) required for solitary extramedullary plasmacytoma (EMP) in the head and neck (HN).

Methods and Materials: Seventeen patients (15 Stage I and 2 Stage II) were treated for HN EMP at our institution between 1979 and 2003. The mean International Commission on Radiation Units (ICRU) dose prescribed to the CTV was 52.6 Gy (range, 40–65 Gy) over 24 fractions (range: 20–30). The Stage II patients received neck irradiation doses of 40 and 60 Gy. A mean dose of 36.4 Gy was used for 5 Stage I patients who received elective neck irradiation. Dose administrated to the CTV was evaluated from dosimetric data or from planning films when dosimetric data were not available. Two groups of patients were distinguished: CTV covered with a dose greater than 40 Gy and CTV covered with a dose greater than 45 Gy.

Results: The 5-year local control was 72.8%. It was 100% for patients who received dose to the CTV ≤ 45 Gy vs. 50% for dose to the CTV <45 Gy (p = 0.034). The prognostic factor for 5-year disease-specific survival (81.6%) was local control (p = 0.058). The prognostic factors for disease-free survival (64.1%) were monoclonal immunoglobulin secretion (p = 0.008) and a CTV dose ≤ 45 Gy (p = 0.056)

Conclusions: Local control of EMP in the HN seems to be improved when the dose to the CTV is ≤ 45 Gy. A minimum dose of 45 Gy should be recommended to the CTV.

Introduction

Solitary extramedullary plasmacytoma (EMP) represents a rare malignant disease. The incidence is 0.04 cases per 100,000 individuals (1). Eighty percent of EMP occurs in the head-and-neck (HN) region (1, 2, 3, 4) and constitutes 0.5% of all the upper respiratory tract malignancies (1). Treatment of EMP in the HN has been previously discussed (1, 2, 5, 6). Radiotherapy is considered the treatment of choice for EMP in the HN (1, 5, 6, 7). The recommended total dose is about 35 to 60 Gy, with a dose threshold greater than 40 Gy (3, 8). Five-year local control varies between 80% and 95%, with a 5-year free of myeloma survival between 60% and 70% (1, 9). However, no general guideline exists for elective neck irradiation (1, 7, 9, 10). The aim of this study was to specify the minimal dose to the clinical target volume (CTV) for HN EMP. We evaluated the dose used on planning films for patients treated before 1986 who had no dosimetry and analyzed the dose received from dosimetric data for patients treated after 1986 in this study.

Section snippets

Methods and materials

Seventeen patients were treated at the Centre Alexis Vautrin, from 1979 to 2003, for an EMP of the HN. The male-to-female ratio was 14:3. The average age was 62.4 years and ranged from 39 to 80 years. EMPs consisted of 7 nasal and paranasal cavity, 7 nasopharynx, 2 oropharynx, and 1 larynx. Fifteen were diagnosed Stage I (tumor confined to the primary site) and 2 Stage II (involvement of the cervical lymph nodes), which included 1 oropharynx and 1 nasal cavity. Five patients had bone

Results

The mean follow-up was 80.5 months (range, 4.5–174 months), with a minimum of 19 months follow-up for all surviving patients. The 5-year and 10-year overall survival rates were 81.6% and 63.4%, respectively (Fig. 1).

Twelve among the 17 patients (70.5%) received a dose ≥40 Gy to the CTV and 9 (52.9%) received a dose ≥45 Gy to the CTV. Eight patients (72.7%) among the 11 with dosimetry received a dose ≥40 Gy to the CTV, and 6 (54.5%) received a dose ≥45 Gy to the CTV.

Discussion

The local control of HN EMP seems to be dependent on the dose delivered to the CTV. A minimum dose of 45 Gy appears to be necessary for local control and disease-free survival of EMP at HN sites. Local control was also found to influence disease-specific survival.

Restraint should be used in the interpretation of these results because this study was a retrospective study with a low number of patients. However, the study concerned a rare tumor, which limited the amount of patient data available.

References (16)

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