High-dose-rate brachytherapy using molds for oral cavity cancer: The technique and its limitations

Evaluation of patients with oral squamous cell carcinoma treated by radical irradiation with mold radiotherapy using a customized device: a retrospective clinical study

Background

It is very important to determine the indication of mold radiotherapy for the radical treatment of oral cancer. We investigated eight patients with oral squamous cell carcinoma who were treated by radical irradiation with mold radiotherapy using a customized device.

Methods

The subject is a case of curable superficial oral cancer of a few millimeters, or cancer of a size that can be cured by the placement of the radiation source. Of the eight patients, six were male and two were female, aged 64–93 years (mean, 78.9 years; median, 73.5 years). The primary sites were the buccal mucosa in three cases, gingiva in two cases, and floor of the mouth, soft palate, and lower lip in one case each. Five cases were in the T1 stage, and the remaining three cases were in T2. With respect to thickness, seven cases were of the superficial type and could not be detected by magnetic resonance imaging or computed tomography, and the remaining case showed a tumor thickness of 7.5 mm. All cases were diagnosed as squamous cell carcinoma by biopsy. Radical irradiation using mold radiotherapy was planned for all eight patients. Irradiation was delivered in 9–10 sessions, with a total dose of 45–50 Gy.

Results

Complete response was attained in six of the eight patients and partial response was observed in two patients, requiring additional treatment.

Conclusion

Since all patients with complete response had superficial cancers, we hypothesized that superficial cancers of the oral cavity with thicknesses of few millimeters could be indicated for mold irradiation. This method can be applied in complicated cases and older patients in whom surgery or chemotherapy may not be feasible. We believe that the results of our clinical studies will be of great help in choosing this method.

High dose rate brachytherapy for oral cancer

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer.

High dose rate brachytherapy using molds after chemoradiotherapy for oral cavity cancer

PURPOSE

The aim of this study was to investigate the role of the combined use of customized molds and a high dose rate (HDR) remote afterloading brachytherapy apparatus with a (192)Ir microsource in the treatment of superficial oral carcinomas after chemoradiotherapy.

MATERIALS AND METHODS

Nine patients with oral squamous cell carcinoma who were treated using this combined technique were analyzed retrospectively. The primary sites of the tumors were the mouth floor, gingiva, and soft palate. For each patient, a customized mold was fabricated in which 2-3 afterloading catheters were placed for the (192)Ir source. Three to eight fractions of 3 Gy, 5 mm below the mold surface, were given following external radiotherapy of 24-50 Gy/2 Gy combined with chemotherapy (peplomycin or taxotere). The total dose of HDR brachytherapy ranged from 9 to 24 Gy.

RESULTS

The 2-year local control probability was 100% and the 2-year cause-specific survival rate was 100%. No serious complications (i.e., ulcer or bone exposure) have been observed thus far during the follow-up period of 29-120 months.

CONCLUSION

HDR brachytherapy using the mold technique after chemoradiotherapy is a safe and excellent method for selected early and superficial oral cavity cancers.

Experience of high-dose-rate brachytherapy for head and neck cancer treated by a customized intraoral mold technique

Radiotherapy of head and neck cancer has become more successful with the advances in treatment modalities and use of a multidisciplinary approach. Higher quality treatment and a team approach to radiotherapy have thus been required for head and neck cancer. This study presents the clinical experience of high-dose-rate (HDR) brachytherapy for head and neck cancer treated by a customized intraoral mold technique. Two patients are reported for whom we created dental prostheses as the radiation carriers for HDR brachytherapy of their head and neck cancers. HDR brachytherapy with the dental prostheses reported here was feasible and effective for eradicating the head and neck cancer. It has been demonstrated that HDR brachytherapy using a customized intraoral technique can be a treatment option for patients who are not candidates for surgery or external irradiation. It is strongly suggested that specialized dentists are needed who are familiar with not only the anatomy and function of the head and neck region but also radiotherapy. Dental radiologists should take responsibility for constructing irradiation prostheses. If they do, they have the potential to improve the quality of life of patients who undergo radiotherapy for head and neck cancer.