In Japan, comprehensive genomic profiling (CGP) testing has been covered by the national health insurance system since 2019, marking six years of implementation. As of May 2025, approximately 100,000 patients have undergone CGP testing. This testing, conducted using tumor tissue or blood samples, has contributed to the identification of novel therapeutic options, accurate diagnoses, and cancer prevention through the disclosure of secondary findings. Additionally, the system for utilizing data centralized at the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) has become operational, positioning Japan's framework to contribute meaningfully to global cancer research and care.
　However, the number of CGP tests performed remains suboptimal, and fewer than 10% of patients receive genome-matched therapies recommended through the testing, indicating a need for fundamental improvements including policy reform. At the same time, it is crucial to leverage the information for individual cancer types to further advance genomic medicine. The author has conducted analyses on the current state of genomic medicine in head and neck cancers, as well as the clinical significance of the resulting genomic profiles, using real-world data accumulated by C-CAT.
　This paper describes the current landscape, challenges, and future directions of cancer genomic medicine focusing on head and neck cancers. It is hoped that this will contribute to the ongoing advancement of genomic medicine in this type of cancer.

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　The development of systemic therapy for squamous cell carcinoma of the oral cavity has advanced alongside that of head and neck squamous cell carcinoma. The clinical introduction of cetuximab, nivolumab, and pembrolizumab has markedly improved treatment outcomes for head and neck squamous cell carcinoma, offering new therapeutic options for high-risk patients who previously had limited access to systemic treatment.
　Notably, immune checkpoint inhibitors not only provide direct therapeutic benefits but also enhance the antitumor activity of subsequent systemic therapies. This underscores the importance of designing comprehensive treatment strategies, including planning the transition from initial to later lines of therapy.
　In recent years, competition in the development of new drugs for head and neck squamous cell carcinoma has intensified, driving an active wave of clinical trials. As new treatment options emerge, the demand for medical professionals with specialized knowledge and experience in clinical practice is expected to grow significantly.

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　Amyloidosis in the oral region often causes symptoms in the tongue, and amyloid deposits in the mandible are extremely rare. Here, we report a case of systemic amyloidosis in the mandible with numb chin syndrome. A 45-year-old man with a medical history of macroglobulinemia was referred to our department with numb chin syndrome as the initial symptom. A biopsy of the mandible suggested AA (Amyloid A) amyloidosis associated with macroglobulinemia. Strict control of macroglobulinemia was needed to improve the numb chin syndrome, and eight courses of R-CHOP therapy were administered. After therapy, the patient's symptoms gradually improved. We continued follow-up for 14 years; the patient has been doing well, and there has been no recurrence.

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　Chronic active Epstein-Barr virus infection (CAEBV) is a disease in which EBV latently infects T cells or NK cells. Subsequently, these infected cells proliferate and infiltrate organs, resulting in a variety of symptoms. CAEBV is rare, with an estimated 100 new cases per year in Japan. The main symptoms are fever, hepatosplenomegaly and lymphadenopathy, and it is extremely rare for the disease to form tumor masses within the oral cavity. We herein present a case of CAEBV that formed a tumor mass in the maxillary gingiva. The patient was 11-years-old, and he complained of swelling of the left maxillary gingiva. A tumor mass with an ulcer was found between the first and second premolars in the upper left gingiva. As a result of a biopsy, EBV infection was identified in T cells, and a pathological diagnosis of EBV-associated lymphoproliferative disorder (EBV-LPD) was made. The patient underwent three courses of chemotherapy (cytarabine, vincristine, and prednisone), and the lesion completely disappeared. Additional examinations showed EBV infection of γδT cells, and he was diagnosed with CAEBV. No recurrence has been observed in three years of follow-up treatment.

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　Antimicrobial-associated epilepsy (AAE) is a drug-induced encephalopathy in which antimicrobial agents cause neurological symptoms such as impaired consciousness, aphasia, involuntary movements, and epileptic seizures. We report a case of AAE caused by cefepime (CFPM) in an oral cancer patient treated with chemoradiotherapy (CRT). A 72-year-old man was referred to our department complaining of swelling and pain in his oral floor. We diagnosed the patient with oral floor squamous cell carcinoma (cT4aN2cM0), and decided to perform CRT with carboplatin because of impaired renal function. During CRT, febrile neutropenia was observed and CFPM was administered. Four days after initiation of CFPM, the patient presented with impaired consciousness, aphasia, seizures, and an abnormal electroencephalogram. Finally, the patient was diagnosed with AAE, and the symptoms disappeared shortly after withdrawal of CFPM. AAE should be considered in patients who develop impaired consciousness while receiving antimicrobial therapy. In patients with impaired renal function, antimicrobial doses should be carefully determined to prevent the development of AAE.

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　Cat-scratch disease (CSD) is caused by Bartonella henselae (B. henselae), and characterized by regional lymphadenopathy and fever. We report a case of a 63-year-old woman diagnosed with CSD using polymerase chain reaction (PCR) analysis of a biopsy specimen from an enlarged cervical lymph node. She subsequently developed mitral valve regurgitation exacerbation and blood culture-negative infective endocarditis (BCNE), presumed to be due to B. henselae infection, necessitating mitral valve replacement surgery.

　She presented to our department with pain in the right submandibular region and cervical lymphadenopathy. Laboratory tests revealed a WBC count of 5,180/μL, 61.8% neutrophils, and CRP at 0.11 mg/dL. Blood cultures were negative. Ultrasonography and CT showed multiple enlarged lymph nodes with internal necrosis in the chin, submandibular, and cervical regions. Her medical history revealed frequent contact with stray cats and scratch wounds on the fingers. A submandibular lymph node biopsy showed granulomatous lymphadenitis on histopathology, and B. henselae was identified by PCR, leading to a definitive diagnosis of CSD.

　Treatment with oral azithromycin was initiated, and further systemic evaluation revealed mitral valve regurgitation and findings suggestive of infective endocarditis. Due to worsening dyspnea and fatigue, mitral valve replacement was performed. Pre-existing mild mitral regurgitation likely worsened due to CSD, leading to blood culture-negative infective endocarditis.

　She is currently under outpatient follow-up, with improvement in both cardiac function and cervical lymphadenopathy, and no recurrence of symptoms.

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　Central carcinoma arising in the mandible is rare. Histopathologically, most are squamous cell carcinoma, and there have been very few reports of undifferentiated carcinoma. Here we report a case of undifferentiated carcinoma arising in the mandible. A 53-year-old man came to our hospital because of hypoesthesia in the right side of the chin in September 2022. Imaging findings revealed a bone defect in the right mandible and cervical lymph node metastases. A biopsy gave a diagnosis of carcinoma. In October, he underwent a tracheostomy, bilateral neck dissection, segmental mandibulectomy and reconstruction with a scapular osteocutaneous flap. The histopathological diagnosis was undifferentiated carcinoma of the mandible. There has been no evidence of recurrence or metastasis for three years after the surgery.

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　Pleomorphic adenoma is the most common benign tumor arising in the salivary glands and generally has a favorable prognosis. However, malignant transformation has been reported in long-standing or recurrent cases, as well as in elderly patients or tumors of large size. In contrast, pseudoepitheliomatous hyperplasia refers to a state in which the epithelium shows marked hyperplasia, representing a benign reactive change that can be easily misinterpreted as squamous cell carcinoma both clinically and histopathologically. We report a case of pleomorphic adenoma with pseudoepitheliomatous hyperplasia that was strongly suspected to be malignant based on clinical and radiological findings. The patient was a 28-year-old man who had noticed palatal swelling for eight years but had left it untreated. He presented after recent rapid tumor growth accompanied by ulcer formation. Imaging revealed suspected invasion of adjacent structures and high FDG uptake on PET-CT, strongly suggesting malignancy. Initial biopsy findings raised suspicion of squamous cell carcinoma; however, histopathological examination of the resected specimen led to the diagnosis of pleomorphic adenoma with pseudoepitheliomatous hyperplasia. Immunohistochemical staining showed neither p53 overexpression nor an increase in Ki-67-positive cells. There has been no recurrence during the 14 months following the operation.

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　Erythropoietic protoporphyria (EPP) is a rare inherited disorder caused by genetic abnormalities affecting genes involved in heme synthesis. Patients with EPP may develop photosensitivity, gastrointestinal disorders, and neurologic complications triggered by light exposure, surgical stress, and the administration of certain drugs, and in some cases may be fatal. Herein we report a case of tooth extraction in a patient with erythropoietic protoporphyria (EPP), in which special attention was paid to perioperative management, particularly concerning light wavelength considerations. The patient was a 33-year-old man diagnosed with pericoronitis of the bilateral mandibular third molars. Extraction under intraveous sedation was planned. The patient was noted to have EPP, so the dermatology department of our hospital was consulted. In this case, drugs that have been reported to be safe were used and the tooth extraction was performed in an environment avoiding exposure to harmful light wavelengths. The procedure was performed without complications. It was considered essential to thoroughly evaluate measures for photosensitivity and carefully select the medications to be used, as well as to ensure adequate preparation prior to the treatment of a patient with EPP.

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