Fewer than 12 lymph nodes can be expected in a surgical specimen after high-dose chemoradiation therapy for rectal cancer

Colorectal carcinoma: Pathologic aspects

Colorectal carcinoma is one of the most common cancers and one of the leading causes of cancer-related death in the United States. Pathologic examination of biopsy, polypectomy and resection specimens is crucial to appropriate patient managemnt, prognosis assessment and family counseling. Molecular testing plays an increasingly important role in the era of personalized medicine. This review article focuses on the histopathology and molecular pathology of colorectal carcinoma and its precursor lesions, with an emphasis on their clinical relevance.

High lymph node yield is related to microsatellite instability in colon cancer

BACKGROUND

Lymph node (LN) yield in colon cancer resection specimens is an important indicator of treatment quality and has especially in early-stage patients therapeutic implications. However, underlying disease mechanisms, such as microsatellite instability (MSI), may also influence LN yield, as MSI tumors are known to exhibit more prominent lymphocytic antitumor reactions. The aim of the present study was to investigate the association of LN yield, MSI status, and recurrence rate in colon cancer.

METHODS

Clinicopathological data and tumor samples were collected from 332 stage II and III colon cancer patients. DNA was isolated and PCR-based MSI analysis performed. LN yield was defined as "high" when 10 or more LNs were retrieved and "low" in case of fewer than 10 LNs.

RESULTS

Tumors with high LN yield were significantly associated with the MSI phenotype (high LN yield: 26.3% MSI tumors vs low LN yield: 15.1% MSI tumors; P=.01), mainly in stage III disease. Stage II patients with high LN yield had a lower recurrence rate compared with those with low LN yield. Patients with MSI tumors tended to develop fewer recurrences compared with those with MSS tumors, mainly in stage II disease.

CONCLUSIONS

In the present study, high LN yield was associated with MSI tumors, mainly in stage III patients. Besides adequate surgery and pathology, high LN yield is possibly a feature caused by biologic behavior of MSI tumors.

Challenging the feasibility and clinical significance of current guidelines on lymph node examination in rectal cancer in the era of neoadjuvant therapy

PURPOSE

We sought to examine the feasibility and clinical significance of current guidelines on nodal assessment in patients with rectal cancer (RC) treated with neoadjuvant radiation.

METHODS

All patients with RC treated with curative surgery from 1991 to 2003 were included. Number of lymph nodes (LNs) assessed was compared between patients who received neoadjuvant therapy and surgery (NEO) and patients who underwent surgery alone (SURG). Impact of node retrieval on node positivity and disease-specific survival (DSS) in NEO patients was assessed.

RESULTS

In total, 708 patients were identified, of whom 429 (61%) were in the NEO group. These patients had significantly fewer nodes assessed than SURG patients (unadjusted mean, 10.8 v 15.5; adjusted mean difference, -5.0 nodes; P < .001). In the NEO group, 63% of patients had fewer than 12 nodes retrieved (P < .001 v SURG). The proportion of patients diagnosed with node-positive disease in the NEO group was significantly and monotonically associated with the number of lymph nodes retrieved, with no plateau in the relationship. Fewer nodes retrieved was not associated with inferior DSS.

CONCLUSION

In a tertiary cancer center, the 12-LN threshold was not relevant and often not achievable in patients with RC treated with neoadjuvant therapy. Lower LN count after neoadjuvant treatment was not associated with understaging or inferior survival. Although we support the critical importance of careful pathologic examination and adequate nodal staging, we challenge the relevance of LN count both in clinical practice and as a quality indicator in RC.

Perspectives on current tumor-node-metastasis (TNM) staging of cancers of the colon and rectum

Improvements in classifications of cancers based on discovery and validation of important histopathological parameters and new molecular markers continue unabated. Though still not perfect, recent updates of classification schemes in gastrointestinal oncology by the American Joint Commission on Cancer (tumor-node-metastasis [TNM] staging) and the World Health Organization further stratify patients and guide optimization of treatment strategies and better predict patient outcomes. These updates recognize the heterogeneity of patient populations with significant subgrouping of each tumor stage and use of tumor deposits to significantly "up-stage" some cancers; change staging parameters for subsets of IIIB and IIIC cancers; and introduce of several new subtypes of colon carcinomas. By the nature of the process, recent discoveries that are important to improving even routine standards of patient care, especially new advances in molecular medicine, are not incorporated into these systems. Nonetheless, these classifications significantly advance clinical standards and are welcome enhancements to our current methods of cancer reporting.

Number of lymph nodes examined and prognosis among pathologically lymph node-negative patients after preoperative chemoradiation therapy for rectal adenocarcinoma

BACKGROUND

Preoperative chemoradiation for rectal cancer can decrease the number of evaluable lymph nodes. Hence, the prognostic role of lymph node evaluation in patients with rectal cancer who receive preoperative chemoradiation is unclear. The authors of this report evaluated the prognostic impact of the number of lymph nodes examined in patients with rectal cancer who had negative lymph nodes based on the pathologic extent of disease (ypN0) after they received preoperative chemoradiation.

METHODS

Between 1990 and 2004, 372 patients with nonmetastatic rectal adenocarcinoma received preoperative chemoradiation followed by mesorectal excision and had ypN0 disease. The median radiation dose was 45 gray, and 68% of patients received adjuvant chemotherapy.

RESULTS

Patients had a median of 7 lymph nodes examined after preoperative chemoradiation. Compared with patients who had ≤7 lymph nodes examined, patients who had >7 lymph nodes had higher 5-year rates of freedom from relapse (86% vs 72%; log-rank P = .005) and cancer-specific survival (95% vs 86%; log-rank P = .0004), but no significant difference was observed in the overall survival rate (87% vs 81%; log-rank P = .07). Multivariate Cox proportional models demonstrated that patients who had >7 lymph nodes examined had a significantly lower risk of relapse (hazard ratio [HR], 0.39; P = .003) and death from rectal cancer (HR, 0.45; P = .04) but a similar risk of all-cause mortality (HR, 0.75; 95% CI, 0.46-1.20; P = .23) compared with patients who had ≤7 lymph nodes examined.

CONCLUSIONS

The number of lymph nodes examined was associated independently with disease relapse and cancer-specific survival in patients with rectal cancer who had ypN0 disease after receiving preoperative chemoradiation. Hence, the authors concluded that the number of negative lymph nodes examined may be a prognostic factor in patients with rectal cancer who receive preoperative chemoradiation.

Laparoscopic versus open surgery for rectal cancer after neoadjuvant chemoradiation: a matched case-control study of short-term outcomes

BACKGROUND

Neoadjuvant chemoradiation (nCRT) currently is commonly incorporated into the multimodal treatment of locally advanced rectal cancers. This study aimed to compare the short-term outcomes and oncologic adequacy of laparoscopic and conventional open surgery for rectal cancer after nCRT.

METHODS

A series of 72 patients who underwent laparoscopic surgery (Lap group) for rectal cancer after nCRT were matched for type of surgery, gender, and American Society of Anesthesiologists (ASA) class with 72 patients who underwent conventional surgery during the same time period (Open group). The short-term outcomes were compared between the two groups of patients.

RESULTS

No significant difference was found between the two groups in terms of age, distance of tumor from the anal verge, body mass index, or posttreatment pathologic stage of the disease. There were significant differences between the Lap and Open groups in terms of blood loss (median: 200 vs 400 ml; P < 0.001), duration of surgery (median: 270 vs 240 min; P < 0.001), time to passing of first flatus (median: 2 vs 3 days; P < 0.001), time to start of normal diet (median: 5 vs 6 days; P < 0.001), and hospital stay (median: 12 vs 15 days; P < 0.001). A significant difference in the number of lymph nodes harvested was not identified between the two groups, although more patients in the Open group had a positive circumferential resection margin than in the Lap group (10 vs 1%; P = 0.03). The short-term benefits of laparoscopic surgery also were observed when the 64 patients who underwent abdominoperineal resection (APR) in each of the two groups were compared separately.

CONCLUSION

Laparoscopic surgery for rectal cancer, especially laparoscopic APR, after nCRT is safe and associated with earlier recovery of bowel function, a shorter hospital stay, and an oncologically adequate specimen compared with conventional open surgery.

[Pathological work-up of rectal cancer following partial/total mesorectal excision]

Total mesorectal excision (TME) refers to the anatomically accurate surgical resection of the rectum from its surrounding fascias and has become the gold standard for treating rectal cancer. The pathologist plays a key role in the assessment of these specimens and good pathological reporting of rectal cancer is essential to achieving the optimum possible results for patients with rectal cancer. In experienced hands, these techniques result in a dramatic improvement in cancer-related cure rates from 45% to 75% and a reduction in pelvic recurrences from 40% to 5%-10%. Moreover, preservation of sexual and urinary functions is possible in the majority of cases. This article reviews the pathological assessment of the TME specimen in detail with regards to current international guidelines and describes its anatomical background. In addition, particular issues relating to margins, lymph node dissection and effects of neoadjuvant therapy are discussed.

Anatomical lymph node mapping in normal mesorectal adipose tissue

PURPOSE

In view of divergent outcomes of surgery for rectal cancer despite standard protocols, the aim of this study was to provide a basis for improving lymph node assessment by defining the number, shape, and distribution of all lymphatic structures in the mesorectum.

METHODS

Cadavers from 6 males and 6 females who died from causes other than colorectal or neoplastic pathologies were studied. Rectum and mesorectum were excised en bloc. The adipose tissue was separated from the rectum and divided into 9 sections before fixing the specimen in paraffin, cutting into smaller portions, and staining with hematoxylin and eosin. Slides were analyzed with an optical microscope, and identified lymph nodes were counted in each section.

RESULTS

The mean age of the deceased was 52.7 (range, 26-65) years. No evidence of previous history of neoplastic pathology or any type of premortal colorectal inflammatory process was found. A total of 412 lymph nodes were identified, with a mean of 34.3 (SD, 2.1; range, 31-37) lymph nodes per cadaver. The mean number of lymph nodes differed significantly across levels of the mesorectum, with 22.2 lymph nodes in the upper, 9.8 in the middle, and 2.3 in the lower sections; 266 (64.6%) of all lymph nodes were located in the upper third of the mesorectum. Distribution density was higher in the proximal posterior sections, with 197 lymph nodes (47.8%) in the upper 2 thirds of the posterior mesorectum. Node diameter was less than 5 mm in 330 (80%) of 412 nodes.

CONCLUSIONS

Our study confirmed that more than 30 lymph node units normally exist in the mesorectal area. In view of previous studies demonstrating advantages of increasing the number of lymph nodes evaluated, staging of rectal cancer might be improved by counting more than 12 lymph nodes per specimen.

Laparoscopic transanal abdominal transanal resection with sphincter preservation for rectal cancer in the distal 3 cm of the rectum after neoadjuvant therapy

BACKGROUND

This study reports the short- and long-term results for a prospective rectal cancer management program using laparoscopic radical transanal abdominal transanal proctosigmoidectomy with coloanal anastomosis (TATA) after neoadjuvant therapy.

METHODS

A prospective database included 102 rectal cancer patients treated with laparoscopic TATA from 1998 to 2008. Patients with distant metastasis at presentation, patients with a tumor more than 3 cm from the anorectal ring, and patients not undergoing neoadjuvant therapy were excluded, leaving 79 patients (54 men and 25 women) with a mean age of 59.2 years (range, 22-85 years) for this study. 13 patients completed neoadjuvant therapy before the original evaluation, and they are excluded from the report of initial clinical assessment. Before treatment, 50 patients were staged as T3 and 16 patients as T2. The mean level in the rectum superior to the anorectal ring was 1.2 cm (range, -0.5 to 3 cm). In terms of fixity, 31 of the tumors were mobile, 27 were tethered, and 8 showed early fixation. Ulceration was absent in 8 cases, minimal in 12 cases, superficial in 7 cases, moderate in 22 cases, and deep in 17 cases. The mean pretreatment tumor size tumor was 4.8 cm (range, 1.5-12 cm). The median external beam radiation was 5,400 cGy (range, 3,000-8,040 cGy), and 77 patients underwent chemotherapy.

RESULTS

The mean follow-up period was 34.2 months (range, 1.9-113.9 months). There were no perioperative mortalities. The conversion rate was 2.5%, and the mean largest incision length was 4.3 cm (range, 1.2-21 cm). For 84% of the patients, the incision was less than 6.0 cm, and 46% of the patients had no abdominal incision for delivery of the specimen. The mean estimated blood loss was 367 ml (range, 75-2,200 ml). All the patients had a temporary diverting stoma. The major morbidity rate was 11%, and the minor morbidity rate was 19%. The major complications included four full-thickness rectal prolapses with repair, one ischemic neorectum with successful reanastomosis, two bowel obstructions, and two failed anastomoses requiring stoma. The ypT stages included 22 complete responses, 12 cases of ypT1, 22 cases of ypT2, 23 cases of ypT3; 65 cases of ypN0, and 14 cases of ypN + (T3 = 7, T2 = 4, T1 = 3). The local recurrence rate was 2.5% (2/79), and the distant metastases rate was 10.1% (8/79). The KM5YAS rate was 97%. Overall, 90% of the patients lived without a stoma. Neorectal loss was due to positive margins or recurrence and was followed by abdominoperineal resection in three cases and ischemia in two cases. The condition of two patients was not reversed due to comorbidities, and one patient had a stoma secondary to bowel obstruction.

CONCLUSION

The study results indicate excellent local recurrence (2.7%) and 5-year survival rates without the need for permanent colostomy in patients with cancers in the distal one-third of the rectum. Laparoscopic total mesorectal excision (TME) with the TATA approach is safe and can be performed laparoscopically. Multi-institutional studies are required to establish the reproducibility of this promising approach.