Tumour Deposits May Have Prognostic Value in Stage III Colorectal Cancer

Author: By Laura Cowen, medwireNews Reporter 

medwireNews: The presence of tumour deposits (TDs) in the pericolonic and perirectal adipose tissue of patients with stage III colorectal cancer is associated with earlier relapse and death, shows a post hoc analysis of the phase III IDEA France study. 

Furthermore, the addition of TD count to lymph node metastasis (LNM) count results in the restaging of some tumours from low-risk pN1 to high-risk pN2, which “could potentially modify the optimal chemotherapy duration in this setting”, write Magali Svrcek, from Sorbonne Université in Paris, France, and co-authors in the Journal of Clinical Oncology. 

The researchers reviewed data for 1942 IDEA France participants who had been randomly assigned to receive 3 or 6 months of treatment with either adjuvant fluorouracil, leucovorin and oxaliplatin or capecitabine and oxaliplatin. 

Of these, 184 (9.5%) had TDs, including 40.2% with stage pN1a/b tumours, 29.9% with pN1c tumours and 29.9% with pN2 tumours. 

The TD-positive patients had significantly more advanced disease, a higher nodal stage and more vascular and perineural invasion than those without TDs. 

They also had significantly worse disease-free survival (DFS) at 3 years than the TD-negative patients, at rates of 65.6% and 74.7%, respectively. 

Moreover, on multivariable analysis, the presence of TDs was associated with a significantly higher risk of recurrence or death (hazard ratio=1.36) and the presence of TDs was associated with worse prognosis across all pN stages, which the investigators say indicates that “TDs should be considered when performing pN staging.” 

The researchers also found that the 35 individuals who were reclassified from stage pN1 to pN2 through the addition of TD count to LNM count had a significantly lower 3-year DFS rate than those remaining at stage pN1 despite the addition of the two markers, at 60.7% versus 79.3%. The reclassified patients had similar DFS, however, to the patients originally classified as stage pN2. 

Magali Svrcek et al explain that the “new category of pN1c was introduced into the seventh edition of AJCC TNM staging system to enable data collection and analysis to be performed to better understand the clinical significance and outcomes of TDs.” 

However, its introduction has been controversial, not least because it was unclear whether patients in the pN1c category require the same adjuvant chemotherapy as individuals with LNM, the authors comment. 

Magali Svrcek et al believe that “both TDs and their numbers should be integrated into pN staging to properly classify stage III tumors into the low-risk and high-risk subgroups.” 

As a consequence “the addition of TDs to the LNM count through reclassification of some low-risk pN1 tumors to high-risk pN2 tumors could potentially modify the optimal chemotherapy duration in patients with CC” they conclude. 

Reference 

Delattre JF, Cohen R, Henriques J. Prognostic value of tumor deposits for disease-free survival in patients with stage III colon cancer: A post hoc analysis of the IDEA France phase III trial (PRODIGE-GERCOR). J Clin Oncol; advance online publication 13 March 2020. doi: 10.1200/JCO.19.01960