The new 'coN' staging system combining lymph node metastasis and tumour deposit provides a more accurate prognosis for TNM stage III colon cancer

OBJECTIVE

Despite controversy over its origin and definition, the significance of tumour deposit (TD) has been underestimated in the tumour node metastasis (TNM) staging system for colon cancer, especially in stage III patients. We aimed to further confirm the prognostic value of TD in stage III colon cancer and to establish a more accurate 'coN' staging system combining TD and lymph node metastasis (LNM).

METHODS

Information on stage III colon cancer patients with a definite TD status was retrospectively collected from the Surveillance, Epidemiology and End Results (SEER) database between 2010 and 2017. The effect of TD on prognosis was estimated using Cox regression analysis. Maximally selected rank statistics were used to select the optimal cut-off value of TD counts. The predictive power of conventional N staging and the new coN staging was evaluated and compared by Akaike's information criterion (AIC), Harrell's concordance index (C-index) and time-dependent receiver operating characteristic (ROC) curves. Clinicopathological data of stage III colon cancer patients in the Xiangya database from 2014 to 2018 were collected to validate the coN staging system.

RESULTS

A total of 39,185 patients with stage III colon cancer were included in our study: 38,446 in the SEER cohort and 739 in the Xiangya cohort. The incidence of TD in stage III colon cancer was approximately 30% (26% in SEER and 30% in the Xiangya database). TD was significantly associated with poorer overall survival (OS) (HR = 1.37, 95% CI 1.31-1.44, p < 0.001 in SEER). The optimal cut-off value of TD counts was 4, and the patients were classified into the TD0 (count = 0), TD1 (count = 1-3) and TD2 (count ≥ 4) groups accordingly. The estimated 5-year OS was significantly different among the three groups (69.4%, 95% CI 68.8%-70.0% in TD0; 60.5%, 95% CI 58.9%-62.2% in TD1 and 42.6%, 95% CI 39.2%-46.4% in TD2, respectively, p < 0.001). The coN system integrating LNM and TD was established, and patients with stage III colon cancer were reclassified into five subgroups (coN1a, coN1b, coN2a, coN2b and coN2c). Compared with conventional N staging, the coN staging Cox model had a smaller AIC (197097.581 vs. 197358.006) and a larger C-index (0.611 vs. 0.601). The AUCs of coN staging at 3, 5 and 7 years were also greater than those of conventional N staging (0.6305, 0.6326, 0.6314 vs. 0.6186, 0.6197, 0.6160). Concomitant with the SEER cohort results, the coN staging Cox model of the Xiangya cohort also had a smaller AIC (2883.856 vs. 2906.741) and a larger C-index (0.669 vs. 0.633). Greater AUCs at 3, 5 and 7 years for coN staging were also observed in the Xiangya cohort (0.6983, 0.6774, 0.6502 vs. 0.6512, 0.6368, 0.6199).

CONCLUSIONS

Not only the presence but also the number of TDs is associated with poor prognosis in stage III colon cancer. A combined N staging system integrating LNM and TD provides more accurate prognostic prediction than the latest AJCC N staging in stage III colon cancer.

Prognostic significance of MR identified EMVI, tumour deposits, mesorectal nodes and pelvic side wall disease in locally advanced rectal cancer

AIM

To study the prognostic significance of MRI identified tumour deposits (TD), extramural vascular invasion (EMVI), lymph node metastases (LNM) and pelvic sidewall (PSW) disease in rectal cancer.

METHODS

This IRB approved study was conducted on patients with stage IIA-IIIC rectal adenocarcinoma treated with neoadjuvant long course chemoradiotherapy (LCCRT) and total mesorectal excision (TME) type of surgery between 2012-2018. A radiologist blinded to outcome reviewed staging and restaging magnetic resonance imaging (MRI) for TD, EMVI, LNM and PSW. The agreement between four radiologists was studied and we obtained outcome data from a prospectively maintained database. The prognostic significance of imaging findings was assessed.

RESULTS

A total of 297 (186 males) patients with a mean age of 47.3 (SD14.4) years were included in the study. The majority had T3 (n = 206) or T4 (n = 59) stage disease. The mean duration of follow-up was 49.3 ± 25 months (6.6-101 months). 5-year overall (OS) and disease-free survival (DFS) was 84% and 74%, respectively. Staging and restaging MRI had EMVI in 49.5% and 31.3%; TD in 47.5% and 31.6%; LNM in 61.1% and 38.1% and PSW in 11.4% and 6.1%. OS was adversely affected by EMVI, TD and PSW with the adjusted HR (aHR) of 3.32, 3.31, 3.27 for staging MRI and 2.99, 3.1, 2.81 for restaging MRI, respectively, p < 0.05. DFS was affected by EMVI (aHR = 1.85, 2.33) and TD (aHR = 1.83, 2.19), p < 0.05. Persistence of these findings after LCCRT led to worst outcome. Intra- and interobserver agreement for EMVI, TD and LN was 0.789, 0.734, 0.406 and 0.449, 0.354, 0.376, respectively, p < 0.001.

CONCLUSIONS

MRI identified that TD, EMVI and PSW disease are independent poor prognostic indicators in rectal cancer patients. Interobserver agreement for these findings was moderate to fair.

Prognostic features of gastro-entero-pancreatic neuroendocrine neoplasms in primary and metastatic sites: Grade, mesenteric tumour deposits and emerging novelties

Updates in classification of gastro-entero-pancreatic neuroendocrine neoplasms better reflect the biological characteristics of these tumours. In the present study, we analysed the characteristics of neuroendocrine tumours that could aid in a more precise stratification of risk groups. In addition, we have highlighted the importance of grade (re)assessment based on investigation of secondary tumour lesions. Two hundred and sixty-four cases of neuroendocrine tumours of gastro-entero-pancreatic origin from three centres were included in the study. Tumour morphology, mitotic count and Ki67 labelling index were evaluated in specimens of primary tumours, lymph node metastases and distant metastases. These variables were correlated with overall survival (OS) and relapse-free survival (RFS). Tumour stage, number of affected lymph nodes, presence of tumour deposits and synchronous/metachronous metastases were tested as possible prognostic features. Mitotic count, Ki-67 labelling index, primary tumour site, tumour stage, presence of tumour deposits and two or more affected lymph nodes were significant predictors of OS and RFS. At the same time, mitotic count and Ki-67 labelling index can be addressed as continuous variables determining prognosis. We observed a very high correlation between the measures of proliferative activity in primary and secondary tumour foci. The presence of isolated tumour deposits was identified as an important determinant of both RFS and OS for pancreatic (hazard ratio [HR] = 7.61, 95% confidence interval [CI] = 3.96-14.6, P < 0.0001 for RFS; HR = 3.28, 95% CI = 1.56-6.87, P = 0.0017 for OS) and ileal/jejunal neuroendocrine tumours (HR = 1.98, 95% CI = 1.25-3.13, P = 0.0036 for RFS and HR 2.59, 95% CI = 1.27-5.26, P = 0.009 for OS). The present study identifies the presence of mesenterial tumour deposits as an important prognostic factor for gastro-entero-pancreatic neuroendocrine tumours, provides evidence that proliferative parameters need to be treated as continuous variables and further supports the importance of grade determination in all available tumour foci.

Prognostic value of tumour deposit and perineural invasion status in colorectal cancer patients: a SEER-based population study

AIMS

The definition of tumour deposit (TD) in colorectal cancer (CRC) was changed recently in the American Joint Commission on Cancer (AJCC) Staging Manual, 7th edition. We aimed to examine the prognostic values of the newly defined TD and perineural invasion (PNI) in this population study.

METHODS AND RESULTS

We identified the incidental CRC cases with known TD or PNI status in the Surveillance, Epidemiology, and End Results (SEER) programme diagnosed in 2010 and 2011. Kaplan-Meier survival analysis and multivariable Cox proportional hazards models were used to estimate overall survivals (OS) and cancer-specific survival (CSS). We found that 6.71% (2774 of 41 323) of the CRC cases were positive for TD and 9.61% (3970 of 41 215) positive for PNI. In multivariable models, TD- and PNI-positive statuses correlated independently with worse 3-year OS [hazard ratio (HR): 1.68, 95% confidence interval (CI): 1.58-1.80 and HR: 1.24, 95%: CI: 1.16-1.32, respectively] and 3-year CSS (HR: 1.79, 95% CI: 1.65-1.94 and HR: 1.28, 95% CI: 1.18-1.38, respectively, P < 0.001 for all). Other independent prognostic factors included age, T category, N category, tumour location and tumour grade, but not gender. TD and PNI correlated with worse OS in all N categories (P < 0.001 for all). TD-associated HR for 3-year OS increases as the N category becomes lower (1.73 in N2, 2.32 in N1 and 3.24 in N0), while rare (1.4%) TD-positive CRC in N0 category should have been assigned to N1c.

CONCLUSIONS

Tumour deposit and PNI correlate independently with worse 3-year OS and CSS. TD appears prognostically more important in the CRC of lower N categories.