Abstract
The key factor mitigating against prognosis in head and neck cancer is nodal metastasis and its management. Neck dissection has been known to play an integral part in this type of cancer management. Submandibular gland preservation during neck dissection and post radiotherapy, have been known to improve subjective symptoms of xerostomia. The authors retrospectively surveyed the involvement of submandibular gland involvement in oral cancer with a view to confirm oncologic safety of submandibular gland preservation, as a first step in a quest to manage radiation induced xerostomia by submandibular gland transfer. The medical and pathological records of oral cancer patients who underwent surgical treatment at the authors’ centre were reviewed retrospectively. 194 patients were included in the study. 229 submandibular glands were excised from the same number of neck dissections. 3 (1.3%) submandibular glands were involved with malignancies microscopically. The mode of involvement was by direct infiltration. In conclusion, no metastasis to submandibular gland was observed. This may suggest the oncologic safety of submandibular gland preservation and transfer.
The prognosis of head and neck cancers in general, is mitigated by primary histopathologic grade and cervical nodal metastasis. As a consequence, neck dissection, a key surgical procedure in oral cancer management has evolved from a radical to a more selective procedure, effective for negative cervical nodes, and viable for positive (N1, N2) cervical nodes.
Submandibular salivary glands (SMGs) are regularly excised in selective neck dissection procedures. This is in part, due to their composition as a level IB neck component, and proximity to the oral cavity, especially in floor of the mouth cancers.
Excision of SMG during surgical management of oral cancers, without adjunct radiotherapy (ART) may lead to subjective symptoms of xerostomia. Residual salivary glands decrease the influence of this subjective xerostomia, characterized by a feeling of dry mouth with or without salivary gland dysfunction. With radiation treatment, which also affect healthy tissues, a radiation dose as little as 35 Gy has been reported to cause permanent salivary gland dysfunction and eventual radiation induced xerostomia. Clinically, this xerostomia is characterized by alteration in taste, mastication, deglutition; loss of appetite and weight loss; all debilitating conditions, adversely affecting the quality of the patient’s life.
About 50% of oral cancer patients undergo ART. This gives an insight into the volume of patients with potential radiation induced xerostomia.
Several treatment options have been employed in the management of radiation induced xerostomia including amifostine, intensity modulated radiation treatment (IMRT)/sparing the parotid gland and pilocarpine. Most showed significant complications, while others provided limited improvement in the patient’s quality of life. Thus, the approach shifted to prevention of xerostomia. One concept was SMG preservation during neck dissection, and transferring the preserved SMG to a less radiated area such as the submental region. Some research reported prevention of radiation induced xerostomia by transferring contralateral or ipsilateral SMG to the submental region and attained a prevention rate of 83%.
There is the possibility of occult metastasis in level I lymph nodes, and the oncologic safety of SMG preservation in oral cavity carcinomas is questioned. SMG tumor involvement has been implicated only by direct invasion and its preservation subsequently advised for early (T1–T2) and N0 head and neck cancers.
In this retrospective study the authors intend to evaluate the oncologic safety of SMG preservation in oral cavity carcinomas. This is a prelude to their quest to add to the clinico-oncologic spectrum of SMG transfer techniques in the management of radiation induced xerostomia at their centre.
Patients and method
This retrospective study reviewed the medical and pathological records of patients who underwent curative wide local excision/composite resection and simultaneous neck dissection of primary oral carcinomas at the Head and Neck Surgical Oncology Service in the authors’ centre from 2009 to 2012.
Exclusion criteria included previously treated oral carcinomas and patients who had previously been irradiated for other head and neck malignancy.
The following data were collated: demographic data; site of primary tumour; pathology of primary tumour; type of neck dissection; pathological staging of primary tumour and nodes according to the 2010 criteria of the American Joint Committee on Cancer (AJCC) staging manual; microscopic nodal extracapsular spread (ECS); and SMG involvement.
Data were analyzed using SPSS for windows version 19.0 software (Statistical Package for Social Science, Chicago, IL, USA). They were analyzed for age, gender, subsite distribution, staging, histologic types, and type of neck dissection. Levels of nodal inolvement/ECS and SMG involvement and simple frequency charts, descriptive statistics and a χ 2 test of comparative statistics were calculated. A level of p < 0.05 was considered to be statistically significant.
Results
194 patients were eligible for the study, comprising 61.9% (120/194) males and 38.1% (74/194) females, with a female to male ratio of 1:1.6. The minimum and maximum ages were 13 years and 90 years, respectively. The mean age was 50.61 ± 13.94 years. The buccal mucosa had the highest sub-site incidence with 36.6% (71/194) of patients followed by the tongue with 26.3% (51/194) of patients. Others were maxilla and maxillary alveolus 9.2% (18), retromolar trigone 8.2% (16), gingivo-buccal sulcus 7.2% (14), mandible and alveolus 6.1% (11), floor of mouth (FOM) 2.1% (4), others 5.2% (10).
22.1% (43/194) of primaries were early stage cancers (pathological T1, T2 and N0) while 77.9% (151/194) of primaries were late stage (pathological any T, N1–3) oral cancers.
For nodal staging, 49.5% (96/194) of patients had pN0, 23.7% (46/194) had pN1, 2.1% (4/194) had pN2a, 18% (35/194) had pN2b, 4.1% (8/194) had pN2c and 2.6% (5/194) had pN3.
229 neck dissections were undertaken, of which 35 patients had bilateral neck dissection. Two of the bilateral neck dissections were ipsilateral radical neck dissections and 227 patients had selective neck dissections. 229 SMG were excised. 98.7% (226/229) of SMG excised, were free of malignancy while 1.3% (3/229) SMG were involved with malignancies.
89.7% (174/194) of patients were diagnosed histologically as having squamous cell carcinomas, 4.6% (9/194) of patients had other forms of carcinomas (adenocarcinomas, adenocystic carcinomas, mucoepidermoid carcinomas), while 5.7% (11/194) primaries were other malignancies.
Level I nodal metastases and SMG involvement
Of the 50.5% (98/194) of patients with neck metastases, 63.3% (62/98) of the patients had level I lymph nodes involvement, of which 62.9% (39/62) were solitary level I node involvement ( p = 0.00). 6.4% (4/62) of cases involved solitary level IA, 32.3% (20/62) of cases involved solitary level IB nodes and 24.2% (15/62) of cases were solitary, unspecified level I nodes. 55% (11/20) of solitary level IB nodes had microscopic ECS (MECS) ( p = 0.000). Further level I nodal distribution and ECS involvement are summarized in Table 1 .
| Nodes | n | Solitary involvement (%) | ECS (%) |
|---|---|---|---|
| IA | – | 6.4 (4/62) | 50 (2/4) |
| IB | – | 32.3 (20/62) | 55 (11/20) |
| I | 62 | 24.2(15/62) a | 63 (39/62) |
51.7% (46/89) of patients in the early primary cancer (T1, T2) and 48.6% (51/105) in the late primary cancer (T3 and T4) presented with nodal metastasis ( p > 0.05). 30.3% (27/89) of early (T1 and T2) and 32.4% (34/105) of late (T3 and T4) cancer patients had level I nodal involvement respectively ( p > 0.05). Incidence of level I involvement by primary sub-site are summarized in Table 2 . The nodal distributions are summarized in Table 3 .
| CPV | No. of pts (%) | Level I involvement (%) | χ 2 ( p < 0.05) |
|---|---|---|---|
| T staging | 0.63 | ||
| T1, T2 | 89(45.9%) | 27(30.3%) | |
| T3, T4 | 105(54.1%) | 34(32.4%) | |
| Primary sub-sites | 0.63 | ||
| BM | 71(36.6%) | 28(39.4%) | |
| TONG | 51 (26.3%) | 13 (25.5%) | |
| MAX | 20 (10.3%) | 4 (20.0%) | |
| RMT | 16 (8.2%) | 4 (25.0%) | |
| GBS | 14 (7.2%) | 6 (42.9%) | |
| MAND | 12 (6.2%) | 1 (8.3%) | |
| FOM | 4 (2.1%) | 2 (50.0%) |
| Levels | n | Ipsilateral nodes | Isolated involvement | Contralateral nodes |
|---|---|---|---|---|
| I | 62 | 59 | 36 (Ipsilateral) | 3 |
| II | 60 | 54 | 13 (Ipsilateral) | 6 |
| III | 42 | 38 | 2 (Ipsilateral) | 4 |
| IV | 16 | 15 | 1 (Ipsilateral) | 1 |
| V | 3 | 2 | 1 (Ipsilateral) | 1 |
Of the 229 SMG histologically examined, 1.3% (3/229) showed local infiltration from the primary and 20.1% (46/229) showed primary tumors changes consistent with chronic reactionary inflammation. The tumors for the three involved SMGs were all staged pT4a with two staged pN2b and one staged pN2c lesion. Two of the primaries were base of tongue cancers and the third was anterior mandibular alveolar cancer. One of the base of tongue cancers was histologically papillary cystadenocarcinoma arising from a minor salivary gland of the base of the tongue infiltrating the right submandibular gland and epiglottis. The other two SMG involved primaries were reported as moderately differentiated squamous cell carcinomas of the mandible and base of tongue infiltrating the left submandibular gland, respectively. All three cases had level IB nodal involvement with MECS with one case being solitary level IB. All three cases/lesions crossed the midline and bilateral neck dissection was performed for all three.
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