Abstract
Background
Prophylactic neck dissection (PND) is indicated when the chance of occult lymph node metastases from head and neck tumors is significant. There is no consensus regarding which tumor size PND would be indicated in cases of lip cancer.
Methods
A total of 139 patients with surgically treated lip cancer were selected. The size of the lesion (T) and the presence of lymph node metastases (N) were assessed by examining the medical records. For analysis purposes, the T2 group was divided into T2a (2 to 3 cm) and T2b (3 to 4 cm).
Results
The following distribution of incidence of neck metastases was observed in the study groups: 11.7% in T1, 9% in T2a, 43.7% in T2b, and 52.2% in T3 + T4. Statistical comparison of the groups (p) revealed the following results: T2a X T2b = 0.03; T2a X T3 + T4 = 0.001.
Conclusion
PND is indicated for tumors larger than 3 cm.
1
Introduction
Cancer of the lip is the most frequent malignant neoplasm of the mouth. The main risk factor for this type of cancer is exposure to ultraviolet radiation, with the lower lip being mainly affected in white men. Squamous cell carcinoma (SCC) is the most prevalent histopathological type of lip cancer . The most important prognostic factor for SCC of the lip is the presence of neck or distant metastases, which directly influences mortality and disease-free time . However, other factors such as tumor size, thickness, location, degree of differentiation, invasion of neighboring structures, perineural and/or vascular infiltration may also affect patient survival .
Although surgical excision of the lesion is the gold standard treatment for most SCCs of the lips, inoperable or unresectable cases could receive radiotherapy in combination or not with chemotherapy .
As well as other SCC of head and neck region, lip SCCs tend to exhibit cervical lymph nodes metastases during their progression. Thus, neck dissection has been adopted in combination with lip lesion resection in situations where these metastases have a significant incidence .
Studies have shown that the pattern of lymphatic drainage of the lips with the production of ganglion metastases occurs for levels I, II and III established by the Sloan Kettering Cancer Center. For this reason, these are the neck levels commonly dissected when there is an indication of prophylactic neck dissection (PND) .
However, doubts exist about what tumor size the risk of micrometastases is sufficiently high to indicate neck dissection. Despite the large number of studies regarding PND , there is no consensus in the literature about when to dissect prophylactically the neck of patients with cancer of the lips.
The purpose of this study was to determine the incidence of neck metastases in cancer of the lip considering the initial size of the tumor and the long-term follow-up of the patients in order to establish an initial tumor size that could justify the indication of PND.
2
Materials and methods
The research protocol was approved by the Research Ethics Committee of the University Hospital and School of Medicine of Ribeirão Preto-USP, protocol 1084/2011. A retrospective study was conducted on 250 medical records of patients with lip cancer who attended the University Hospital of the School of Medicine of Ribeirão Preto-USP, from 1986 to 2011. Only previously untreated SCC cases were selected. Exclusion criteria were: patients previously submitted to surgical or non-surgical treatment, patients with other types of tumors, cases of recurrence of the primary tumor, impossibility of surgical treatment, or patients who were not followed up for at least one year. The 139 patients selected were submitted to a biopsy of the primary lesion, to preoperative laboratory tests and to surgical treatment with tumor exeresis and neck dissection when they presented neck metastases or with PND in more advanced tumors. Data regarding the clinical and pathological TNM classification of the American Joint Committee on Cancer (AJCC), the location of the lesion (lower lip, upper lip or lip commissure) and follow-up time were extracted from the medical records.
For analysis, the patients were assigned to the following groups according to the classification of the American Joint Committee on Cancer (AJCC) regarding tumor (T) size: T1, lesions of up to 2 cm; T2, lesions ranging from more than 2 cm to 4 cm; T3, lesions of more than 4 cm, and T4, lesions that invaded structures adjacent to the primary site. Group T2 was subdivided into T2a, lesions ranging from more than 2 cm to 3 cm, and T2b , lesions ranging from more than 3 cm to 4 cm. The presence of cervical metastases was classified as N + and their absence as N−. The patients were evaluated regarding the presence or absence of metastases after long-term follow-up. The information was organized on Excel® spreadsheets and analyzed statistically by the two-tailed chi-square or two-tailed Fisher exact test. The Openepi* software for epidemiologic statistics was used for statistical analysis.
2
Materials and methods
The research protocol was approved by the Research Ethics Committee of the University Hospital and School of Medicine of Ribeirão Preto-USP, protocol 1084/2011. A retrospective study was conducted on 250 medical records of patients with lip cancer who attended the University Hospital of the School of Medicine of Ribeirão Preto-USP, from 1986 to 2011. Only previously untreated SCC cases were selected. Exclusion criteria were: patients previously submitted to surgical or non-surgical treatment, patients with other types of tumors, cases of recurrence of the primary tumor, impossibility of surgical treatment, or patients who were not followed up for at least one year. The 139 patients selected were submitted to a biopsy of the primary lesion, to preoperative laboratory tests and to surgical treatment with tumor exeresis and neck dissection when they presented neck metastases or with PND in more advanced tumors. Data regarding the clinical and pathological TNM classification of the American Joint Committee on Cancer (AJCC), the location of the lesion (lower lip, upper lip or lip commissure) and follow-up time were extracted from the medical records.
For analysis, the patients were assigned to the following groups according to the classification of the American Joint Committee on Cancer (AJCC) regarding tumor (T) size: T1, lesions of up to 2 cm; T2, lesions ranging from more than 2 cm to 4 cm; T3, lesions of more than 4 cm, and T4, lesions that invaded structures adjacent to the primary site. Group T2 was subdivided into T2a, lesions ranging from more than 2 cm to 3 cm, and T2b , lesions ranging from more than 3 cm to 4 cm. The presence of cervical metastases was classified as N + and their absence as N−. The patients were evaluated regarding the presence or absence of metastases after long-term follow-up. The information was organized on Excel® spreadsheets and analyzed statistically by the two-tailed chi-square or two-tailed Fisher exact test. The Openepi* software for epidemiologic statistics was used for statistical analysis.
3
Results
Of the 139 patients selected, 126 (91%) had SCC of the lower lip, seven (5%) had SCC of the upper lip, and six (4%) had SCC on the lip commissure. Mean follow-up time was 36.1 months. The T size and the presence of lymph node metastases (N) of the patients were as presented in Table 1 , which shows that there was a steady increase in the incidence of metastases with increasing tumor size and T2 already had a high rate of metastases that would justify neck dissection. However, when T2 was divided into T2a and T2b ( Table 2 ), we observe that most metastases occurred in tumors larger than 3 cm (T2b).
