Surgical management of primary colorectal cancer

Lynch Syndrome-Impact of the Type of Deficient Mismatch Repair Gene Mutation on Diagnosis, Clinical Presentation, Surveillance and Therapeutic Approaches

In today's world, with its continuing advancements in genetics, the identification of Lynch syndrome (LS) increasingly relies on sophisticated genetic testing techniques. Most guidelines recommend a tailored surveillance program, as well as personalized prophylactic and therapeutic approaches, according to the type of dMMR gene mutation. Carriers of path_MLH1 and path_MSH2 genes have a higher risk of developing colorectal cancer (CRC), despite intensive colonoscopic surveillance. Conversely, carriers of path_MSH6 and path_PMS2 genes have a lower risk of developing CRC, which may be due to their lower penetrance and later age of onset. Thus, carriers of path_MLH1 or path_MSH2 would theoretically derive greater benefits from total colectomy, compared to low-risk carriers (path_MSH6 and path_PMS2), in which colonoscopic surveillance might achieve an efficient prophylaxis. Furthermore, regarding the risk of endometrial/ovarian cancer development, there is a global agreement to offer both hysterectomy and bilateral salpingo-oophorectomy to path_MLH1, path_MSH2 and path_MSH6 carriers after the age of 40. In patients with CRC, preoperative knowledge of the diagnosis of LS is of tremendous importance, due to the high risk of metachronous CRC. However, this risk depends on the type of dMMR gene mutation. For carriers of the high-risk variants (MLH1, MSH2 and EPCAM) who have already developed colon cancer, it is strongly recommended a subtotal or total colectomy is performed, while partial colectomy followed by endoscopic surveillance is an appropriate management approach to treat colon cancer in carriers of the low-risk variants (MSH6 and PMS2). On the other hand, extended surgery for index rectal cancer (such as total proctocolectomy) is less effective than extended surgery for index colon cancer from the point of view of metachronous CRC risk reduction, and is associated with a decreased quality of life.

Precision Medicine for CRC Patients in the Veteran Population: State-of-the-Art, Challenges and Research Directions

Colorectal cancer (CRC) accounts for ~9% of all cancers in the Veteran population, a fact which has focused a great deal of the attention of the VA's research and development efforts. A field-based meeting of CRC experts was convened to discuss both challenges and opportunities in precision medicine for CRC. This group, designated as the VA Colorectal Cancer Cell-genomics Consortium (VA4C), discussed advances in CRC biology, biomarkers, and imaging for early detection and prevention. There was also a discussion of precision treatment involving fluorescence-guided surgery, targeted chemotherapies and immunotherapies, and personalized cancer treatment approaches. The overarching goal was to identify modalities that might ultimately lead to personalized cancer diagnosis and treatment. This review summarizes the findings of this VA field-based meeting, in which much of the current knowledge on CRC prescreening and treatment was discussed. It was concluded that there is a need and an opportunity to identify new targets for both the prevention of CRC and the development of effective therapies for advanced disease. Also, developing methods integrating genomic testing with tumoroid-based clinical drug response might lead to more accurate diagnosis and prognostication and more effective personalized treatment of CRC.

Fluorescently labeled chimeric anti-CEA antibody improves detection and resection of human colon cancer in a patient-derived orthotopic xenograft (PDOX) nude mouse model

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate a new fluorescently labeled chimeric anti-CEA antibody for improved detection and resection of colon cancer.

METHODS

Frozen tumor and normal human tissue samples were stained with chimeric and mouse antibody-fluorophore conjugates for comparison. Mice with patient-derived orthotopic xenografts (PDOX) of colon cancer underwent fluorescence-guided surgery (FGS) or bright-light surgery (BLS) 24 hr after tail vein injection of fluorophore-conjugated chimeric anti-CEA antibody. Resection completeness was assessed using postoperative images. Mice were followed for 6 months for recurrence.

RESULTS

The fluorophore conjugation efficiency (dye/mole ratio) improved from 3-4 to >5.5 with the chimeric CEA antibody compared to mouse anti-CEA antibody. CEA-expressing tumors labeled with chimeric CEA antibody provided a brighter fluorescence signal on frozen human tumor tissues (P = 0.046) and demonstrated consistently lower fluorescence signals in normal human tissues compared to mouse antibody. Chimeric CEA antibody accurately labeled PDOX colon cancer in nude mice, enabling improved detection of tumor margins for more effective FGS. The R0 resection rate increased from 86% to 96% with FGS compared to BLS.

CONCLUSION

Improved conjugating efficiency and labeling with chimeric fluorophore-conjugated antibody resulted in better detection and resection of human colon cancer in an orthotopic mouse model.

Successful fluorescence-guided surgery on human colon cancer patient-derived orthotopic xenograft mouse models using a fluorophore-conjugated anti-CEA antibody and a portable imaging system

BACKGROUND

Fluorescence-guided surgery (FGS) can enable successful cancer surgery where bright-light surgery often cannot. There are three important issues for FGS going forward toward the clinic: (a) proper tumor labeling, (b) a simple portable imaging system for the operating room, and (c) patient-like mouse models in which to develop the technology. The present report addresses all three.

MATERIALS AND METHODS

Patient colon tumors were initially established subcutaneously in nonobese diabetic (NOD)/severe combined immune deficiency (SCID) mice immediately after surgery. The tumors were then harvested from NOD/SCID mice and passed orthotopically in nude mice to make patient-derived orthotopic xenograft (PDOX) models. Eight weeks after orthotopic implantation, a monoclonal anti-carcinoembryonic antigen (CEA) antibody conjugated with AlexaFluor 488 (Molecular Probes Inc., Eugene, OR) was delivered to the PDOX models as a single intravenous dose 24 hours before laparotomy. A hand-held portable fluorescence imaging device was used.

RESULTS

The primary tumor was clearly visible at laparotomy with the portable fluorescence imaging system. Frozen section microscopy of the resected specimen demonstrated that the anti-CEA antibody selectively labeled cancer cells in the colon cancer PDOX. The tumor was completely resected under fluorescence navigation. Histologic evaluation of the resected specimen demonstrated that cancer cells were not present in the margins, indicating successful tumor resection. The FGS animals remained tumor free for over 6 months.

CONCLUSIONS

The results of the present report indicate that FGS using a fluorophore-conjugated anti-CEA antibody and portable imaging system improves efficacy of resection for CEA-positive colorectal cancer. These data provide the basis for clinical trials.

Fluorescence-guided surgery of human colon cancer increases complete resection resulting in cures in an orthotopic nude mouse model

BACKGROUND

We inquired if fluorescence-guided surgery (FGS) could improve surgical outcomes in fluorescent orthotopic nude mouse models of human colon cancer.

METHODS

We established fluorescent orthotopic mouse models of human colon cancer expressing a fluorescent protein. Tumors were resected under bright light surgery (BLS) or FGS. Pre- and post-operative images with the OV-100 Small Animal Imaging System (Olympus Corp, Tokyo Japan) were obtained to assess the extent of surgical resection.

RESULTS

All mice with primary tumor that had undergone FGS had complete resection compared with 58% of mice in the BLS group (P = 0.001). FGS resulted in decreased recurrence compared with BLS (33% versus 62%, P = 0.049) and lengthened disease-free median survival from 9 to >36 wk. The median overall survival increased from 16 wk in the BLS group to 31 weeks in the FGS group. FGS resulted in a cure in 67% of mice (alive without evidence of tumor at >6 mo after surgery) compared with only 37% of mice that underwent BLS (P = 0.049).

CONCLUSIONS

Surgical outcomes in orthotopic nude mouse models of human colon cancer were significantly improved with FGS. The present study can be translated to the clinic by various effective methods of fluorescently labeling tumors.

Recent advances in the management of rectal cancer

Recently there have been significant advances in the management of patients with rectal cancer, attributed mainly to advances in surgical techniques and pre- and postoperative therapy. This review addresses some of these advances and their impact on the prognosis for rectal cancer patients.

A exenteração pélvica no tratamento do câncer de reto estádio T4: experiência de 15 casos operados

RACIONAL: A exenteração pélvica tem sido a melhor opção terapêutica radical para o tratamento dos tumores de reto T4. No entanto, essa operação ainda permanece com mortalidade significante e alta morbidade. OBJETIVO: Relatar série de 15 casos de exenteração pélvica para tumores de reto T4, analisando a morbidade, mortalidade e sobrevida dos pacientes. MÉTODOS: Foram estudados 15 pacientes com câncer de reto T4 no Serviço de Cirurgia Geral - Oncocirurgia do Hospital do Servidor Publico Estadual de São Paulo, SP, submetidos a exenteração pélvica no período de 1998 e 2006. Sete eram do sexo masculino enquanto oito eram do sexo feminino, com média de idade de 65 anos. Todos apresentavam sintomas incapacitantes. As operações foram: exenteração infra-elevadora (n = 6), exenteração supra-elevadora (n = 4), exenteração posterior (n = 3) e exenteração posterior com cistectomia e ureterectomia parciais (n = 2). RESULTADOS: A média de tempo cirúrgico foi de 403 minutos (280-485). A média de sangramento foi de 1620 mL (300-4800). A mortalidade pós-operatória foi de 6,66% (n = 1). A morbidade pós-operatória foi de 53,3% (n = 8). Os exames histológicos evidenciaram que todas as ressecções foram R0. Envolvimento linfonodal foi observado em quatro pacientes (26,66 %) sendo que todos faleceram em decorrência da neoplasia. A sobrevida global em cinco anos foi de 35,7%. CONCLUSÃO: A exenteração pélvica ainda apresenta alta morbidade, no entanto permanece justificada, pois pode conferir maior controle do câncer de reto T4 em longo prazo.

Impact of cytokeratin-20 and carcinoembryonic antigen mRNA detection by RT-PCR in regional lymph nodes of patients with colorectal cancer

The reported rates for tumour cell involvement in the locoregional lymph nodes of colorectal cancer vary greatly, depending on the method used and case selection. In order to further evaluate the clinical value of molecular biologic detection of tumour cells we investigated 102 histologically tumour-free (pN0) regional lymph nodes from 51 consecutive, completely resected (UICC R0) colorectal carcinoma specimens for the presence of tumour cell mRNA by RT-PCR specific for carcinoembryonic antigen (CEA) and cytokeratin 20 (CK-20). Two lymph nodes located nearest to the primary tumour were investigated in each case. CK-20 mRNA was found in 31 of 51 patients (60.8%) and CEA mRNA in 30 of 51 patients (58.8%), respectively. Identical transcription patterns of CK-20 and CEA mRNA (both positive or both negative) were found in 38 of 51 patients (74.5%). There was a significantly higher proportion of cases with CEA positivity in the lymph nodes of tubulopapillary than of mucinous adenocarcinomas (P< 0.03). Detection of CK-20 and CEA mRNA correlated in nine of 12 cases (75.0%) with the risk of tumour recurrence (not significant) and showed a tendency towards shorter disease-free survival by univariate analysis (not significant). Our data indicate that CK-20 and CEA mRNA detection by RT-PCR may prove useful for the prediction of tumour recurrence of patients with pN0 colorectal carcinoma, although neither reach statistical significance in this series of patients.