title: Prognostic value of tumor shrinkage versus fragmentation following radiochemotherapy and surgery for rectal cancer.
abstract: Most patients with rectal cancer receive neoadjuvant radiochemotherapy (RCT), causing a variable decrease in tumor mass. We evaluated the prognostic impact of pathologic parameters reflecting tumor response to RCT, either directly or indirectly. Seventy-six rectal cancer patients receiving neoadjuvant RCT between 2006 and 2009 were included. We studied the association between disease-free survival (DFS) and the "classical" clinicopathologic features as well as tumor deposits, circumferential resection margin (CRM), Dworak regression grade, and tumor and nodal downstaging. Patients with tumor downstaging had a longer DFS (p = 0.05), indicating a more favorable prognosis when regression was accompanied by a decrease in tumor infiltrative depth, referred to as tumor shrinkage. Moreover, tumor downstaging was significantly associated with larger CRM and nodal downstaging (p = 0.02), suggesting that shrinkage of the primary tumor was associated with a decreased nodal tumor load. Higher Dworak grade did not correlate with tumor downstaging, nor with higher CRM or prolonged DFS. This implies that tumor mass decrease was sometimes due to fragmentation rather than shrinkage of the primary tumor. Lastly, the presence of tumor deposits was clearly associated with reduced DFS (p = 0.01). Assessment of tumor shrinkage after RCT via tumor downstaging and CRM is a good way of predicting DFS in rectal cancer, and shrinkage of the primary tumor is associated with a decreased nodal tumor load. Assessing regression based on the amount of tumor in relation to stromal fibrosis does not accurately discern tumor fragmentation from tumor shrinkage, which is most likely the reason why Dworak grade had less prognostic relevance.
authors.affiliation: Department of Pathology, Calmette Hospital, #3, Monivong Boulevard, Phnom Penh, Cambodia, hav_monirath@yahoo.com.
authors.forename: Monirath
authors.initials: M
authors.lastname: Hav
authors.forename: Louis
authors.initials: L
authors.lastname: Libbrecht
authors.forename: Karen
authors.initials: K
authors.lastname: Geboes
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Ferdinande
authors.forename: Tom
authors.initials: T
authors.lastname: Boterberg
authors.forename: Wim
authors.initials: W
authors.lastname: Ceelen
authors.forename: Piet
authors.initials: P
authors.lastname: Pattyn
authors.forename: Claude
authors.initials: C
authors.lastname: Cuvelier
mesh_terms: D000368:Aged; D059248:Chemoradiotherapy / Q000379:methods*; D013505:Digestive System Surgical Procedures; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods*; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*