Treatment of Stage I Hard Palate Cancer with High-Dose-Rate Brachytherapy Using Molds: Cost-Based Perspective.

INTRODUCTION: Treatment of T1N0M0 (T1 = greatest tumor size < 2 cm, N0 = regional lymph nodes not palpable by clinical examination, M0 = No evidence of distant metastasis) (Green FL, Page DL, Fleming ID, Fritz AG, Balch CM, Haller DG, Morrow M. AJCC Cancer Staging Manual. New York: Springer; 2002) lesions of hard palate carcinoma by radiotherapy carries equal results with the advantage of cosmesis and can avoid surgical complications. External beam radiotherapy (EBRT) will last for 6-8 weeks. Feasibility of high-dose-rate (HDR) intraoral mold brachytherapy is an alternative to EBRT, which is highly effective and reduces treatment time and is also cost-effective one, which can be practiced in a center without Linac facilities.
MATERIALS AND METHODS: Custom-made surface molds were prepared for each patient with dental wax, and HDR after loading tubes were placed as per tumor volume. After simulation, with the help of simulation check films, treatment was planned with PLATO Treatment Planning System (TPS) and optimization was carried out.
RESULTS: We treated six cases of T1N0M0 hard palate carcinoma by HDR intraoral mold brachytherapy. A total dose of 42-45 Gy in 14-15 fractions with 3 Gy per fraction, two fractions per day with a gap of minimum 6 h was administered between two fractions. (Gray [Gy] is the unit of absorbed dose of radiation by tissues. A total radiation dose of 42-45 Gy will be delivered as per radiobiological principles, in divided number of fractions, thereby the given dose of radiation will kill the major portion of the tumor cells, which were in various sensitive phases of cell cycle and at the same time, less damage to the normal tissues. The time between two fractions of radiation is 6 h, which is the experimentally proven optimal time for recovery of normal tissues from radiation damage and tumor tissues to enter into the sensitive phases of the cell cycle to radiation damage-late G2 and S phases). There was confluent mucositis and all the patients had a complete response and none of the patients had relapse.
CONCLUSION: Early (T1N0M0) lesions of hard palate carcinoma with HDR intraoral mold brachytherapy will shorten overall duration of treatment time with excellent local control and toxicities as compared with EBRT.

INTRODUCTION

Treatment of skin cancers, cancers of oral cavity, oropharynx, and palate region by surface mold brachytherapy is a well-described technique in radiotherapy. The surface mold brachytherapy can be used alone.[123] At MNJ Institute of Oncology and Regional Cancer Center, Red Hills, Hyderabad, Telangana, India, a total number of 7500 new cases are registered per year. Of which, 20% of cases are of head and neck region and majority (90%) of cases are in advanced stage at presentation. Early carcinomas of hard palate (Stage I) region account for less than 0.5% of early stages of head and neck cancers (10%) and rarely metastasize to regional lymph nodes.

Carcinomas of hard palate region account for less than 0.5% of head and neck region in MNJ Institute of Oncology and Regional Cancer Center. These tumors are easily accessible to vision, thereby to early diagnosis and treatment. External beam radiotherapy (EBRT) gives excellent results but it carries a longer duration of treatment. Surface mold brachytherapy is a practical mode of treatment and a good alternative to EBRT to the patients, where we can avoid multiple visits and prolonged duration of overall treatment duration. This is a practical way of treatment in centers where appropriate EBRT energies for treatment were not available.

Superficial cancers were reacted by Iridium (Ir)-192 interstitial brachytherapy[45] or with mold brachytherapy with gamma ray emitters.[6] Nowadays, the present HDR brachytherapy machine uses a source, usually Ir-192, with few millimeters length and <1 mm diameter and with high activity.[7] High-dose-rate (HDR) brachytherapy equipment were accompanied by Treatment Planning System (TPS), calculation of dose distribution, and optimization for individual cases,[8910] thereby quality assurance and precision planning. In this article, we describe a custom-made low-cost HDR brachytherapy treatment technique useful in the treatment of six cases of hard palate carcinoma (T1N0M0).

MATERIALS AND METHODS

We treated total six[6] patients with T1 lesions of hard palate carcinoma between 2004 and 2009 at MNJ Institute of Oncology and Regional Cancer Center. The patients with histopathologically proven hard palate carcinoma were selected. After clinical examination, those having T1 lesions (as per tumor node metastasis staging system) without palpable neck nodes were included for protocol treatment. Contrast enhanced computed tomography (CECT) head and neck was carried out to exclude bone and paranasal sinus and lymph nodal involvement. Baseline blood investigations and chest X-Ray was carried out. After pre-radiotherapy dental prophylaxis and extractions, individual’s hard palate impression was prepared with dental molding material for each patient. Tumor was traced on the mold. HDR source catheters were placed 0.8–1 cm apart based on the tumor size and with treatment, margin in the grooves was made manually and the flexible interstitial brachytherapy catheters were fixed in the grooves, which were parallel to each other. Before and after placing the catheters, dummy source checks were carried out to know the patency of the catheters. Dental mold with catheters was covered with dental wax to reduce discomfort to the patient. There is a problem with incisor teeth and anterior palate, causing some areas of irregularity of the arch of the surface, leading to smaller diameter tubes so as to pass the source to pass through the tubes. This will lead to a gap between channels and surface of the molds. The patients were simulated with intraoral wax mold and with dummy sources. The target volume was defined. Treatment planning and optimization were carried out with PLATO TPS. The patients were treated with a total dose of 42–45 Gy/14–15 fractions, with 3 Gy per fractions with two fractions per day with a minimum interval between two fractions being 6 h. The severity of oral mucosal reactions was recorded during treatment and after completion of treatment. During radiotherapy, patients were kept on mouth gargles and prophylactic oral antifungal. During treatment, patients who were experiencing pain because of mucosal reactions were given Xylocaine spray 5–10 min before placing mold. The minimum follow-up period was 2 years and maximum follow-up period was 5 years [Figures 1–6].

Figure 1

Before treatment

Figure 6

Response to treatment

Prepared individual patient mold

Pretreatment simulator check film

Computerized treatment planning system final approved plan

Mucosal reactions with treatment

RESULTS [T]

A total of six patients were studied, age of these patients ranged between 50 and 70 years. All of them had T1 lesions as per the inclusion criteria. One patient each had squamous cell carcinoma with histopathological grade 2 lesion and grade 3 lesion, whereas the remaining four patients had grade 1 lesion. These patients were followed up for 3–5 years and complete remission was seen in all the cases. All the patients received the radiation dose of 3 Gy per fraction with two fractions per day with minimum 6 h interval for 14–15 fractions over 10–14 days. None of the patients had a recurrence during the follow-up period. We produced an acceptable plan for all the six patients. The variation in the surface of lesions and the variation in implant distance lead to generate a plan, which delivers a uniform dose to the whole area.

DISCUSSION

Early cancers of the oral cavity can be effectively managed with surgery or radiation. Surgery will be in the form of wide local excision, leading to significant functional or cosmetic problems. Even it is very difficult to achieve negative margin. For early T1–2 oral cancers, combination of external beam radiation plus/minus brachytherapy boost usually in the form of interstitial brachytherapy had 74%–92% control rates.[111213] Sufficient evidence was available to prove that low-dose-rate (LDR) brachytherapy delivered higher doses of radiation for local control of oropharyngeal cancers and for limiting toxicity.[14151617] The local control and complication rates were similar with LDR and HDR brachytherapy.[1819] To minimize morbidity, moderate doses of EBRT and smaller doses of HDR brachytherapy are used to prevent the wide spread lymphatic involvement. In the present study of hard palate carcinoma with minimal lymph node involvement, HDR mold barchytherapy was used more effectively. In 2004, before initiating treatment, we communicated with Subir Nag, regarding evidence of using HDR brachytherapy as a sole modality for dosage schedule.[20] In selected patients with early and superficial lesions, the use of surface mold applicators has advantages such as avoiding surgical procedures and its sequelae, treatment on outpatient basis, and reduction in an overall treatment time of 10–14 days as compared to 6–8 weeks when compared to that of external beam radiation treatment. This option is particularly useful for elderly patients and patients with poor performance status. Follow-up examination can detect a local recurrence at the earliest and surgical salvage can be carried out without much more complications as we can limit high-dose volume by brachytherapy. Even we can reserve external beam radiation as an option for second primaries of head and neck.[21]

The cost of HDR brachytherapy equipment is much lower than the cost of linear accelerators with intensity modulated radiotherapy or three-dimensional conformal radiotherapy and both the facilities were not available at MNJ Institute of Oncology and Regional Cancer Center during the study period. The mold materials used were the cheapest. Hence, this is a low-cost and effective therapy.

CONCLUSION

The radiotherapy is equally effective in the treatment of early hard palate carcinomas. The HDR mold brachytherapy with custom-made applicators will be helpful in uniform dose distribution to the tumor with sharp fall of dosage at the edges of the applicators. Use of custom-made mold was reproducible for daily treatment and helpful for high-precision treatment, thereby achieving excellent local control, mucosal complications comparable to that of EBRT, less overall treatment duration, which can be carried out on outpatient department basis, and low cost as compared to conformal therapies.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Table 1

Patient Characteristics

Patient no.	1	2	3	4	5	6
Age (years)	50	62	70	56	60	65
T stage	T1	T1	T1	T1	T1	T1
H.P Grade	1	3	1	2	1	1
Follow up (Years)	5	5	3	4	4	5
Response	CR	CR	CR	CR	CR	CR
Dose Per # (Gy)	3	3	3	3	3	3
No of fractions	15	15	14	15	14	15
Time (days)	12	10	14	11	12	12
Mucocitis	confluent	confluent	confluent	Confluent	confluent	confluent