[Clinicopathological study of safe resectional margin in mid and low rectal cancer after neoadjuvant chemoradiotherapy].

OBJECTIVES: To investigate the regression pattern of mid and low rectal cancer treated with neoadjuvant chemoradiotherapy and then to provide the pathological proofs for reasonable resectional margin in rectal cancer surgery. METHODS: Forty cases of mid and low rectal cancer patients received concurrent chemoradiotherapy and then underwent radical operation. The whole-mount serial sections of resected rectal cancer specimen were stained with cytokeratin antibody using immunohistochemical techniques to show the residual cancer cells under the mucosa. The microscopic measurement was performed to determine the reverse infiltration of cancer cells in the rectal wall and to describe the cancer cells scatter ways in the cancer mass. The Ki-67 immunohistochemical stain was also performed to show the proliferation activity of residual cancer cells after neoadjuvant chemoradiotherapy. RESULTS: The length of specimen was shrinking continuously during the pathologic section production and the shrink rate was 18%. There were remanent cancer cells which showed positive Ki-67 expression and the chemoradiotherapy decreased the Ki-67 expression significantly. The lower edge of remaining ulcers or scars could be used as the reference point from which the cancer infiltration could be measured. According to our measurement, the average reverse infiltration of cancer cells in the whole-mount section was (6.1±4.7) mm, the deepest one was 11.0 mm in the section which could be converted into fresh bowel length of 12.98 mm. The pathology showed that the residual cancer cells scattered in the fibrous tissue of ulcers, scars and manifested a regression of spatial distribution. CONCLUSIONS: The rectal cancers show regression in different degrees after neoadjuvant chemoradiotherapy. The residual cancer cells in the fiber tissues manifest proliferation activity. The distal end of resection should be at least 2 cm away from the lower edge of ulcers or scars of primary tumor in the rectal wall in patients after neoadjuvant chemoradiotherapy. The circumferential resection margin should include all the fibrous scar of the tumor area to ensure the remove of tumor cells completely.

PIK3CA and TP53 gene mutations in human breast cancer tumors frequently detected by ion torrent DNA sequencing.

Breast cancer is the most common malignancy and the leading cause of cancer deaths in women worldwide. While specific genetic mutations have been linked to 5-10% of breast cancer cases, other environmental and epigenetic factors influence the development and progression of the cancer. Since unique mutations patterns have been observed in individual cancer samples, identification and characterization of the distinctive breast cancer molecular profile is needed to develop more effective target therapies. Until recently, identifying genetic cancer mutations via personalized DNA sequencing was impractical and expensive. The recent technological advancements in next-generation DNA sequencing, such as the semiconductor-based Ion Torrent sequencing platform, has made DNA sequencing cost and time effective with more reliable results. Using the Ion Torrent Ampliseq Cancer Panel, we sequenced 737 loci from 45 cancer-related genes to identify genetic mutations in 105 human breast cancer samples. The sequencing analysis revealed missense mutations in PIK3CA, and TP53 genes in the breast cancer samples of various histologic types. Thus, this study demonstrates the necessity of sequencing individual human cancers in order to develop personalized drugs or combination therapies to effectively target individual, breast cancer-specific mutations.