In many countries, treatment for cancer is performed based on staging systems in which the degree of cancer development is defined objectively. A common staging system is thus needed to compare outcomes. The staging system for colorectal cancer in Japan has been made to enhance consistency with the TNM classification, and the categorization of metastatic lymph nodes and depth of invasion have been revised in recent years. Although these are important factors that determine disease stage, relationships between each factor and recurrence have shown differing prognoses. In our retrospective study, the prognosis of a group with only one metastatic lymph node was significantly better compared to a group with ≧2 metastatic lymph nodes. In addition, rectal cancer with mesorectal extension >5 mm showed low relapse-free survival rates and high recurrence rates. The validity of staging systems should thus be inspected from various perspectives.

A rare case of neuroendocrine small cell carcinoma (SmCC) of the breast is reported. A 51-year-old postmenopausal woman noticed a nodule approximately 3 cm in diameter in her right upper breast. Histologically, the tumor consisted of small ovoid to pleomorphic cells with hyperchromatic nuclei, and a large central area was occupied by acellular amorphous tissue. Extensive lymphatic permeation was seen around the tumor. Invasive and in situ ductal carcinoma foci were not observed in and surrounding the tumor. Immunohistochemically, estrogen and progesterone receptors and HER2/neu were all negative in the tumor cells. Synaptophysin and chromogranin A were diffusely positive in the tumor cells. Cytokeratin 8 was only positive in a few tumor cells. The labeling indices of Ki-67 and p53 were high in the tumor. Postoperatively, systemic studies including positron emission tomography were performed but failed to reveal any other possible primary sites, including lung. Based on these findings, the tumor was diagnosed as neuroendocrine primary SmCC of the breast. Postoperatively, the patient received a course of weekly paclitaxel. However, pelvic bone metastasis was identified on a bone scintigram 1 year after surgery. Mammary SmCC showing high Ki-67 and p53 index should be treated carefully because of their aggressive clinical behavior.

We report a 17-year-old woman with refractory high-grade breast cancer who died early after surgery, with reference to the histogenesis of the cancer. Macroscopically, the tumor was cystic, composed of a mixture of solid and myxomatous areas. Histologically, the tumor exhibited ductal structures and areas with squamoid features. Cancer cells were markedly atypical and polymorphic, and included a mixture of bizarre and eosinophilic cells with rhabdoid feature-like free cells. Immunohistochemically, cytokeratin (CK) 8, CK 18, 34 beta E12, CD10, involucrin, CK14, and vimentin were partially positive, whereas estrogen and progesterone receptors and HER-2 were negative. These findings suggest an undifferentiated cancer whose cells have multilineage potential to differentiate into mesenchymal, basal, and squamoid cells, and it was diagnosed as pleomorphic carcinoma, which is a histological type hitherto unreported in young girls. The cancer was refractory to treatment, and the patient died 1 year and 5 months after surgery despite chemotherapy and radiotherapy.