Among 479 cases with oral squamous cell carcinoma from 1998 to 2007 in the Department of Maxillofacial Surgery, Tokyo Medical and Dental University Dental Hospital, multiple primary cancers were observed in 60 (12.5%) patients. The incidence of multiple primary cancers was high in males; the male-female ratio was 4 : 1. Thirty-three (48.5%) of 68 lesions were found in the digestive tract. The period between detection of first cancer and development of second cancer was significantly shorter in the group in which oral cancer occurred first than in the group in which other cancers occurred first. The survival rates of patients with multiple primary cancers were significantly lower than those of patients without multiple primary cancers. Significant risk factors in the development of multiple primary cancers included age, sex, lesion and smoking.

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Keratocystic odontogenic tumor (KCOT) is a benign uni- or multicystic, intraosseous tumor of odontogenic origin. KCOT is lined with parakeratinized stratified squamous epithelium. Multiple KCOTs are known as one of the stigmata of the inherited nevoid basal cell carcinoma syndrome (NBCCS). The most important clinical features of KCOT are its potential for locally aggressive and infiltrative behavior and its tendency to recur.
In this retrospective study, we examined 90 KCOTs in 68 patients (39 males, 29 females) treated at the Department of Oral and Maxillofacial Surgery, University Hospital of Dentistry, Tokyo Medical and Dental University from 2001 to 2010. Of the 68 patients, 8 (3 males, 5 females) were NBCCS patients and had 30 KCOTs.
Recurrence was found in 24 of 90 tumors (26.7%). Tumors that were marsupialized before enucleation had a lower recurrence rate (16.1%) than those that were not marsupialized before enucleation (34.5%). Tumors with radical treatment of neighboring teeth when enucleating had a lower recurrence rate (3.4%) than those with conservative treatment (37.7%).
Recurrences were mainly found in the area associated with tooth roots that were not removed during the surgical treatment. This was thought to be due to difficult access and thus incomplete removal of all tumor tissue.
The period between primary enucleation and recurrence ranged from 6 months to 5 years, and the majority of recurrences developed within 3 years after enucleation. So, long-term follow-up at regular intervals for at least 3 years after surgery is recommended.

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We analyzed the clinical features of 45 patients with intraoral minor salivary gland carcinoma treated at our department between April 2001 and March 2011.
The buccal mucosa was the most common site accounting for 13 cases, followed by the floor of the mouth in 8 cases. Of the 45 cases, 16 cases were classified as stage I, 13 as stage II, 3 as stage III, 12 as stage IVA, and 1 as stage IVB. Histologically, mucoepidermoid carcinoma (MEC) was the most common disease (n=22), followed by adenoid cystic carcinoma (ACC) (n=13) and polymorphous low-grade adenocarcinoma (n=4).
Forty-four patients underwent radical surgery and one patient received irradiation as the initial treatment. Local recurrence developed in 4 cases of MEC and each case of ACC and adenocarcinoma, NOS. These four MECs consisted of 2 (40.0%) high grade malignancies and one case each of intermediate (20.0%) and low grade malignancy (9.1%), both of which except for the high grade MECs were salvaged by additional surgery. Neck failure following neck dissection performed on 16 cases occurred in one case each of high and intermediate grade MEC, and the latter was salvaged by additional surgery. Lung metastasis occurred in 3 cases of ACC, resulting in death without locoregional disease. Five-year and 10-year disease-specific survival rates were 90.1% and 66.9%.
These results suggest that radical surgery is needed for local control of high grade MEC, and the treatment modality should be developed for lung metastasis in ACC.

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Epithelial-myoepithelial carcinoma (EMC) is a rare malignant salivary gland neoplasm accounting for approximately 1% of all salivary gland tumors. EMC is typically found in the parotid gland. In this report, we present a case of double cancer with EMC in the submandibular gland and lung cancer.
The patient was a 57-year-old woman. She had been aware of a left submandibular mass for ten years. An elastic and hard thumb-sized mass in the submandibular region was palpated. CT examination revealed neoplastic lesions in the left submandibular gland and the left upper lung. In April 2008, based on the diagnosis of tumor of the left submandibular gland and metastatic lung cancer in the left upper lobe, excision of the submandibular gland tumor was performed. Subsequently, a left superior lobectomy was performed in the Department of Thoracic Surgery in our hospital in May 2008. Postoperative microscopic examination revealed that the submandibular tumor was characterized by a bilayer structure composed of outer clear myoepithelial cells and inner ductal cells. The pathological diagnosis was EMC. The lung tumor was diagnosed as bronchioloalveolar carcinoma, and the two lesions were independent of each other.
The postoperative course was uneventful. The patient has been well and free from the disease for 3 years postoperatively.

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