Nancy Kemeny

Colon cancer stem cells are believed to originate from a rare population of putative CD133+ intestinal stem cells. Recent publications suggest that a small subset of colon cancer cells expresses CD133, and that only these CD133+ cancer cells are capable of tumor initiation. However, the precise contribution of CD133+ tumor-initiating cells in mediating colon cancer metastasis remains unknown. Therefore, to temporally and spatially track the expression of CD133 in adult mice and during tumorigenesis, we generated a knockin lacZ reporter mouse (CD133lacZ/+), in which the expression of lacZ is driven by the endogenous CD133 promoters. Using this model and immunostaining, we discovered that CD133 expression in colon is not restricted to stem cells; on the contrary, CD133 is ubiquitously expressed on differentiated colonic epithelium in both adult mice and humans. Using Il10-/-CD133lacZ mice, in which chronic inflammation in colon leads to adenocarcinomas, we demonstrated that CD133 is expressed on a full gamut of colonic tumor cells, which express epithelial cell adhesion molecule (EpCAM). Similarly, CD133 is widely expressed by human primary colon cancer epithelial cells, whereas the CD133- population is composed mostly of stromal and inflammatory cells. Conversely, CD133 expression does not identify the entire population of epithelial and tumor-initiating cells in human metastatic colon cancer. Indeed, both CD133+ and CD133- metastatic tumor subpopulations formed colonospheres in in vitro cultures and were capable of long-term tumorigenesis in a NOD/SCID serial xenotransplantation model. Moreover, metastatic CD133- cells form more aggressive tumors and express typical phenotypic markers of cancer-initiating cells, including CD44 (CD44+CD24-), whereas the CD133+ fraction is composed of CD44lowCD24+ cells. Collectively, our data suggest that CD133 expression is not restricted to intestinal stem or cancer-initiating cells, and during the metastatic transition, CD133+ tumor cells might give rise to the more aggressive CD133(- )subset, which is also capable of tumor initiation in NOD/SCID mice.

PURPOSE: To determine if fluorouracil (5-FU) plus high-dose leucovorin (LV) enhances local response in patients receiving preoperative radiation therapy (RT) for adenocarcinoma of the rectum, we compared the degree of downstaging in patients receiving preoperative RT with or without chemotherapy. PATIENTS AND METHODS: For this comparison, three groups of patients who were treated with identical doses and techniques of preoperative pelvic RT (total dose of 5,040 cGy) were examined. Group 1 included 20 patients with unresectable disease who received combined RT and LV/5-FU. Group 2 included 11 patients with unresectable disease who received preoperative RT. Group 3 included 21 patients with invasive, resectable, primary disease who received preoperative RT. RESULTS: Patients with unresectable disease who received LV/5-FU had a higher rate of pathologic complete response (20% v 0%) and a lower incidence of positive nodes (30% v 64%) compared with those who did not receive chemotherapy. Even when the most favorable group of patients was included (group 3), patients who received LV/5-FU still had a higher complete response rate (20% v 6%) and a lower incidence of positive nodes (30% v 53%) compared with those who received RT without LV/5-FU. Of those patients with initially unresectable disease, the resectability rate was higher in those who received LV/5-FU compared with those who did not receive LV/5-FU (90% v 64%). Patients who received LV/5-FU experienced slightly more grade 1 to 2 fatigue, stomatitis, nausea, and grade 3 diarrhea, tenesmus, and dysuria. CONCLUSIONS: Despite the fact that patients who received chemotherapy (group 1) had more advanced disease compared with those with resectable disease (group 3), the addition of LV/5-FU increased the resectability and downstaging rates. The ultimate impact of a complete response as well as a decrease in the incidence of pelvic nodes on local control and survival remains to be determined. However, given the enhancement of down-staging in patients with unresectable rectal cancer, we are encouraged by the combined modality approach.

To decrease the toxicity of hepatic arterial fluorodeoxyuridine (FUDR) administered through an Infusaid pump (Shiley Infusaid, Inc., Norwood, MA), 50 patients with liver metastases from colorectal cancer were selected randomly to receive FUDR, 0.3 mg/kg/d, for 14 of 28 days, with or without a total dose of 20 mg of hepatic arterial dexamethasone for 14 of 28 days. Patients were stratified according to the percentage of liver involvement by tumor and the perfusion pattern on macroaggrated albumin perfusion scan (MAA) scan. There was a trend toward decreased frequency of bilirubin levels in the group receiving dexamethasone plus FUDR versus the group receiving FUDR alone (9% and 30%, respectively, had a 200% or greater increase from baseline; P = 0.07). Patients in the group treated with dexamethasone and FUDR received higher doses of FUDR in the second, third, fifth, and sixth months than those receiving FUDR alone; however, this was statistically significant only in the fifth month (percentages of planned dose received: 42% and 19%, respectively; P = 0.05), and there was no overall difference for the total 6-month period. The complete and partial response rates were increased in patients receiving dexamethasone and FUDR versus FUDR alone (8% and 63% versus 4% and 36%, respectively; P = 0.03), and there was a trend toward increased survival with the addition of dexamethasone (median, 23 months and 15 months, respectively; P = 0.06). In conclusion, the use of hepatic arterial dexamethasone is associated with an increased response rate and a trend toward increased survival and decreased bilirubin levels. Therefore, the authors recommend additional investigation of the use of dexamethasone with chemotherapy to treat hepatic metastases.

PURPOSE: We report the downstaging, sphincter preservation, acute toxicity, and preliminary local control and survival results of preoperative 5-fluorouracil (5-FU), low-dose leucovorin (LV), and concurrent radiation therapy followed by postoperative LV/5-FU for treatment of patients with clinically resectable T3 rectal cancer. MATERIALS AND METHODS: A total of 32 patients received two monthly cycles of preoperative LV/5-FU (bolus daily X 5). Radiation therapy (5,040 cGy) began concurrently on day 1. Postoperatively, patients received a median of two monthly cycles of LV/5-FU (range, 0-10). RESULTS: The complete response rate was 9 percent pathologic and 13 percent clinical, for a total of 22 percent. Total Grade 3+ acute toxicity during the preoperative combined modality segment was 25 percent (8/32). Of the 20 patients who were thought to initially require an abdominoperineal resection and for whom the intent of treatment was sphincter preservation, 17 (85 percent) were able to undergo sphincter-preserving surgery. With a median follow-up of 22 (3-59) months, none have developed local failure, and the three-year actuarial disease-free survival rate was 60 percent. CONCLUSION: Our data reveal encouraging downstaging, sphincter preservation and acute toxicity with this regimen. Additional follow-up is needed to assess the long-term local control and survival rates.

In Brief Objectives: The impact of margin width on overall survival (OS) in the context of other prognostic factors after resection for colorectal liver metastases is unclear. We evaluated the relationship between resection margin and OS utilizing high-resolution histologic distance measurements. Methods: A single-institution prospectively maintained database was queried for all patients who underwent an initial complete resection of colorectal liver metastases between 1992 and 2012. R1 resection was defined as tumor cells at the resection margin (0 mm). R0 resection was further divided into 3 groups: 0.1 to 0.9 mm, 1 to 9 mm, and 10 mm or greater. Results: A total of 4915 liver resections were performed at Memorial Sloan Kettering Cancer Center between 1992 and 2012, from which 2368 patients were included in the current study. Half of the patients presented with synchronous disease, 43% had solitary metastasis, and the median tumor size was 3.4 cm. With a median follow-up for survivors of 55 months, the median OS of the R1, 0.1 to 0.9 mm, 1 to 9 mm, and 10 mm or more groups was 32, 40, 53, and 56 months, respectively (P < 0.001). Compared with R1 resection, all margin widths, including submillimeter margins correlated with prolonged OS (P < 0.05). The association between the margin width and OS remained significant when adjusted for all other clinicopathologic prognostic factors. Conclusions: Resection margin width is independently associated with OS. Wide margins should be attempted whenever possible. However, resection should not be precluded if narrow margins are anticipated, as submillimeter margin clearance is associated with improved survival. The prolonged OS observed with submillimeter margins is likely a microscopic surrogate for the biologic behavior of a tumor rather than the result of surgical technique. This study evaluated the impact of margin status in 2368 patients undergoing hepatic resection for colorectal liver metastases. Prolonged survival is independently associated with margin clearance down to submillimeter width. These findings suggest that margin clearance is important and that submillimeter margin clearance is likely a microscopic surrogate for the biologic behavior of a tumor.