Takashi Miyakawa

Publications (2)8.66 Total impact

• Article: K-ras mutation in tamoxifen-related endometrial polyps.

  Toru Hachisuga, Takashi Miyakawa, Hiroshi Tsujioka, Shinji Horiuchi, Makoto Emoto, Tatsuhiko Kawarabayashi
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  ABSTRACT: K-ras mutation is thought to occur at an early stage of neoplastic progression in the endometrium. The authors investigated mutations in codon 12 of K-ras in tamoxifen (TAM)-related endometrial polyps. DNA was extracted from 11 frozen endometrial polyps from TAM-treated patients with breast carcinoma. Mutations were detected using the mutant allele-specific amplification method. The results subsequently were analyzed for correlations with immunohistochemical data that were obtained using antibodies against estrogen receptors (ERs; alpha and beta forms), progesterone receptors (PRs; A and B forms), and Ki-67. Mutations in codon 12 of K-ras were observed in 7 of 11 TAM-related endometrial polyps. Expression levels of ER-alpha and PR-B were high in the glandular epithelium and low in the stroma. PR-A expression was high in both the glandular epithelium and the stroma. In the glandular epithelium, expression of ER-beta appeared to be lower than expression of ER-alpha. The Ki-67 index in the glandular epithelium ranged from 2 to 38, whereas the index ranged from 0 to 4 in the stroma (P < 0.01). The incidence of mutations in codon 12 of K-ras in TAM-related endometrial polyps (64%) was greater than the incidence of these same mutations in sporadic endometrial hyperplasias (4.5-23%). High expression levels of ER-alpha, PR-A, and PR-B in the glandular epithelium were observed in all polyps, regardless of K-ras codon 12 mutation status and Ki-67 index. The authors' findings may support the hypothesis that the polyp-carcinoma sequence partly indicates the development of endometrial carcinoma in postmenopausal women who have been treated with TAM.
  Cancer 12/2003; 98(9):1890-7. · 4.77 Impact Factor
• Article: A pure nongestational choriocarcinoma of the ovary diagnosed with DNA polymorphism analysis.

  Hiroshi Tsujioka, Hitoshi Hamada, Takashi Miyakawa, Toru Hachisuga, Tatsuhiko Kawarabayashi
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  ABSTRACT: Choriocarcinoma arises in the ovary from gestational or nongestational origin. Nongestational choriocarcinoma of the ovary is extremely rare and the pure type is less frequent than the mixed type with other germ cell tumors. Diagnosis of pure nongestational choriocarcinoma is very difficult without genetic analysis. We report a pure nongestational choriocarcinoma primarily arising in a 19-year-old woman's ovary. Following abdominal operative procedure, careful examination of the tumor revealed pure choriocarcinoma without combination of other germ cell tumors. We confirmed its nongestational origin by DNA polymorphism analysis. Multiple courses of chemotherapy with an EMA/CO regimen were effective for this case. Genetic analysis is useful tool in determining the origin of choriocarcinoma. We could distinguish the genetic origin of this tumor analyzing only two or three appropriate VNTR loci.
  Gynecologic Oncology 07/2003; 89(3):540-2. · 3.89 Impact Factor