British Journal of Radiology (2003) 76, 414-417
© 2003 British Institute of Radiology
doi: 10.1259/bjr/20227256
Iridium-192 implantation for T1 and T2a carcinoma of the tongue and floor of mouth: retrospective study of the results of treatment at the Royal Berkshire Hospital
J C Wadsley1,
M Patel2,
C D C Tomlins2 and
J Q Gildersleve1
1 Berkshire Cancer Centre and 2 Department of Oral Surgery, Royal Berkshire Hospital, Reading, UK
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Abstract
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Carcinomas of the tongue and floor of mouth are relatively rare tumours, which may be treated using several modalities. We reviewed the results of iridium wire implants performed at the Royal Berkshire Hospital between 1994 and 2000. 24 patients had iridium wire implants as primary treatment for tongue and floor of mouth cancers. Four patients were treated after excision biopsy with close or involved margins. One patient was treated for a recurrence after surgery. The median age at treatment was 61 years. There were 18 men and 11 women. 21 patients had tumours of the tongue and eight of the floor of mouth. 13 had T1 tumours and 11 had T2a tumours. The median follow up was 42 months. The primary tumour was controlled in 22 of the 29 patients by the implant alone. Of the seven patients with local recurrence four were successfully salvaged with surgery. The acturarial 2 year survival rates were: overall survival 81%, disease specific survival 91%, local recurrence free survival 85% and nodal relapse free survival 76%. The recorded complication rate was low, one patient developing radionecrosis of the mandible at 7 years post implant. We believe these results show that brachytherapy remains a treatment option for patients with early tongue carcinoma with a high rate of local control and low toxicity.
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Introduction
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Squamous cell carcinoma of the tongue and floor of mouth are relatively rare cancers with an estimated incidence of 1.1 per 100 000 in the UK. More men are affected than women. As with other squamous carcinomas of the head and neck, smoking and alcohol are strong risk factors [1]. There are numerous options for treatment of these cancers including surgery, laser resection, cryotherapy and radiotherapy. Radiotherapy may be delivered by external beam treatment or brachytherapy. Brachytherapy has the advantages of allowing preservation of the structure and function of the tongue and avoiding the marked toxicity of external beam radiotherapy to the oral mucosa. It is an appropriate primary treatment for small (<3 cm) well circumscribed lesions in accessible locations. Because these are relatively unusual cancers with numerous treatment options it is vital that they are managed within specialist head and neck units, and that a careful multidisciplinary assessment is made before deciding on the most appropriate treatment strategy [2].
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Methods
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Patients
Between June 1994 and October 2000 29 patients had iridium wire implants for carcinomas of the anterior tongue and floor of mouth at the Royal Berkshire Hospital. A further three had brachytherapy boosts after external beam radiotherapy for tumours larger than 3 cm and are not included in this analysis. All of the implants were performed by a single clinical oncologist (JQG). Patients were selected at a multidisciplinary head and neck clinic, attended by an oncologist and maxillofacial and ENT surgeons.
All 29 patients had histologically confirmed squamous carcinomas of the tongue or floor of mouth. All but one of these patients had clinically negative neck nodes at presentation. One patient presented with a small (1 cm) carcinoma of the tongue with a palpable neck node and was managed with a radical neck dissection and iridium wire implant to the primary tumour. At neck dissection he was found to have three involved nodes and subsequently received post operative radiotherapy to the neck only. This patient is included in our analysis.
The median age of these 29 patients was 61 years (range 28–87 years). There were 18 men and 11 women. 21 had carcinomas of the tongue and 8 carcinomas of the floor of mouth. 13 patients had T1 (less than 2 cm) tumours and 11 T2a (2–3 cm). Four patients were treated after excision biopsy with close or involved margins and one patient was treated for a recurrence following previous surgical treatment. Median follow-up for patients still alive was 42 months (range 9–90 months).
Treatment regimen
The iridium wire implants were inserted under general anaesthesia using stainless steel gutter guides. A single row of iridium wire hairpins was used in all cases, yielding a two plane implant. The number of hairpins required was determined prior to the procedure, according to the size of the tumour, allowing for a separation of 12–15 mm between the hairpins. In three cases only one hairpin was required. 13 required two hairpains and 13 required three hairpins. The length of the hairpins ranged between 3 cm and 5 cm.
Once the implant was in place orthogonal radiographs were taken. The tumour doses were calculated by computer dosimetry, according to the Paris system and were prescribed to the 85% (reference) isodose. The target tumour dose was 65 Gy delivered at 42 cGy h-1. Wires were ordered with the approriate activity to deliver this dose rate.
The mean reference dose delivered was 68.3 Gy (range 63–81 Gy), with a mean dose rate of 47 cGy h-1 (range 38–69 cGy h-1). Total treatment times were in the range 114–187 h.
Following the implant therapy patients were followed regularly, initially monthly, in the multidisciplinary clinic. If there was any suspicion of residual or recurrent tumour biopsies were taken promptly.
Statistics
Actuarial survival rates were calculated using the Kaplan–Meier method. Survivals were calculated from the date that the implant was inserted. Local recurrence free survival was defined as survival without relapse in the tongue or floor of mouth. Disease specific survival was defined as time to death related to the cancer. Patients who died from intercurrent causes were censored.
In view of the relatively short median follow up (42 months) survivals are quoted at 2 years. Full survival curves are also presented.
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Results
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Local control
The primary tumour was controlled by the iridium implant alone in 22 of 29 patients at last follow up. Two patients had isolated local recurrences at 6 and 22 months, which were successfully surgically salvaged. One elderly patient had a late isolated local recurrence, nearly 5 years after the implant. In view of her co-morbidities full surgical resection at this stage was considered inappropriate and she was treated by laser debulking alone. Three patients had local recurrence associated with either preceeding or simultaneous nodal relapse. In two cases local control was regained with surgery but both patients subsequently died of distant disease. The third patient suffered repeated local recurrences after surgery but was well and disease free at last follow up. One patient had residual disease in the tongue at biopsy 3 months after the implant and at subsequent surgery was found to have extensive nodal involvement. He subsequently died of progressive disease.
In summary, of seven patients experiencing local recurrence, local control was successfully regained with surgery in four cases and only one patient died with active local disease.
The 2 year actuarial local recurrence free survival was 85% (Figure 1
). No association could be demonstrated between the size of primary tumour or the reference dose delivered and likelihood of local relapse, probably because both of these variables lay within a narrow range.
Nodal relapse
Seven of the 29 patients experienced subsequent nodal relapse. Two patients, developing a single involved node at 5 and 31 months, had radical neck dissections and have remained disease free since then. A further patient developed a local recurrence in the tongue and two involved neck nodes 6 months after her implant. These were managed surgically and she was disease free at the most recent follow up, 54 months later, having had further local recurrences treated surgically. Four patients developed more extensive nodal involvement and in spite of surgery went on to develop distant disease and died of their cancer. The actuarial nodal relapse free rate at 2 years was 76% (Figure 2).
Survival
Actuarial overall survival was 81% at 2 years (Figure 3). Of the eight patients who died, three died of other causes with no sign of active malignant disease. Disease specific survival was therefore greater; 91% at 2 years (Figure 4).
Complications
We found a low rate of recorded complications. Three patients had ulcers at the treatment site more than 3 months after the implant, but in all cases these settled with conservative treatment. Two patients were noted to have developed marked telangiectasia at the treatment site which was asymptomatic. Only one patient, who had been treated for a floor of mouth cancer, developed radionecrosis of the mandible. This was diagnosed 7 years after the implant. To date it has been managed conservatively.
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Discussion
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The main treatment options for cancers of the tongue and floor of mouth are radiotherapy and surgery. Although no randomized evidence is available, retrospective series have suggested that the two treatments yield similar results in terms of local control and survival. Mitchell and Crighton [3] report a small series of T2 carcinomas of the tongue treated in Edinburgh. Disease free survival rate was 50% for surgery and 31% for radiotherapy and overall survival 64% for surgery and 62% for radiotherapy, neither difference was statistically significant. Radiotherapy has the advantage of conservation of tongue volume and morphology, making a good functional outcome more likely. Brachytherapy has the advantage over external beam therapy of delivering a high dose to the tumour with a low dose to surrounding tissues, and the radiobiological advantage of a short overall treatment time.
It is, however, vital that cases are carefully selected for brachytherapy. Shibuya et al [4] reported that infiltrative tumours have much worse outome than superficial tumours with brachytherapy. 5 year primary control was 85% for superficial tumours, 79% for exophytic tumours and only 45% for infiltrative tumours, irrespective of stage.
The results of our iridium wire implants compare favourably with those of other published series. Dearnaley et al [5] report a series from the Royal Marsden Hospital. Amongst their "good prognosis" group (T1N0 and T2N0 tumours) the local recurrence free rate was 75% at 5 years, with 89% of local recurrences within 2 years of treatment. Disease specific survival was 72% at 5 years. Mazeron et al [6] present a French series with local recurrence rates of 14% for T1, 11% for T2a and 26% for T2b tumours. Some patients in their series were treated with doses up to 75 Gy, with significantly greater toxicity. Radiation necrosis was recorded in 18% of T1, 29% of T2a and 47% of T2b tumours.
We believe the complication rate for our series is acceptable, with only one of 29 patients developing radionecrosis. Although retrospective review is notoriously unreliable at detecting low grade toxicity, it is unlikely that any other instances of radionecrosis would be unrecorded. However, given the relatively short follow up of some patients, and the late presentation of osteoradionecrosis, it is possible that more complications may develop with time.
The management of the node-negative neck in tongue cancer remains controversial. There are varying reports of incidence of nodal recurrence, which is undoubtedly related to the size of the primary tumour. Shibuya et al [4] report nodal relapse rates without prophylactic treatment to the neck of 31% for T1, 41% for T2a and 51% for T2b tumours. Some would feel that these rates justify prophylactic treatment of the neck nodes, either with surgery or radiotherapy. Whilst this treatment reduces incidence of nodal relapse, there has not been any survival benefit demonstrated and the treatment is not without significant morbidity. A recent report has shown increased risk of stroke after radiotherapy to the neck [7], with a cumulative risk of 12% at 15 years. We believe our series has an acceptably low rate of nodal relapse, and three of the seven patients were successfully surgically salvaged.
The vital role of the specialist centre and multidisciplinary team in the management of these patients must be emphasized, both in intial assessment and selection of appropriate therapy and in follow up, allowing prompt surgical salvage if necessary. A team of people with expertise in brachytherapy treatment is required to be able to perform the implants. In summary, our series of iridium wire implants for carcinomas of the tongue and floor of mouth shows a good rate of local control with preservation of the function of the tongue. Surgical salvage was possible in some cases in the event of local or nodal recurrence. The complication rate was acceptably low.
Received for publication February 26, 2002.
Accepted for publication April 10, 2003.
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References
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- Robertson AG, Robertson C, Soutar DS, et al. Treatment of oral cancer: the need for defined protocols and specialist centres. Variations in the treatment of oral cancer. Clin Oncol 2001;13:409–15.[CrossRef]
- Mitchell R, Crighton LE. The management of patients with carcinoma of the tongue. Br J Oral Maxillofac Surg 1993;31:304–8.[Medline]
- Shibuya H, Hoshina M, Takeda M, et al. Brachytherapy for stage I and II oral tongue cancer: an analysis of past cases focusing on control and complications. Int J Radiat Oncol Biol Phys 1993;26:51–8.[Medline]
- Dearnaley DP, Dardoufas C, A'Hearn RP, Henk JM. Interstitial irradiation for carcinoma of the tongue and floor of mouth: Royal Marsden Hospital experience 1970–1986. Radiother Oncol 1991;21:183–92.[Medline]
- Mazeron JJ, Crook JM, Marinello G, et al. Prognostic factors of local outcome for T1, T2 carcinomas of the oral tongue treated by iridium 192 implantation. Int J Radiat Oncol Biol Phys 1990;19:281–5.[Medline]
- Dorresteijn LDA, Kappelle AC, Boogerd W, et al. Increased risk of ischaemic stroke after radiotherapy on the neck in patients younger than 60 years. J Clin Oncol 2002;20:282–8.[Abstract/Free Full Text]
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Abstract
Introduction
