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. 2025 Mar;23(1):82-89.
doi: 10.1111/vco.13032. Epub 2024 Dec 4.

Do Pre-Treatment Biopsy Characteristics Predict Early Tumour Progression in Feline Diffuse Large B Cell Nasal Lymphoma Treated With Radiotherapy?

Valerie J Poirier  1 , Valeria Meier  2 , Michelle Turek  3 , Neil Christensen  4 , Jacqueline Bowal  1 , Matthew D Ponzini  5 , Stefan M Keller  6
Affiliations

Do Pre-Treatment Biopsy Characteristics Predict Early Tumour Progression in Feline Diffuse Large B Cell Nasal Lymphoma Treated With Radiotherapy?

Valerie J Poirier et al. Vet Comp Oncol. 2025 Mar.

Abstract

The standard of care treatment for localised feline nasal lymphoma (FeNL) is radiation therapy (RT). Early local or systemic failure occurs in 17%-45% of cats treated with RT with or without chemotherapy. The aim of this study was to determine if pre-treatment biopsy characteristics could predict early tumour progression in FeNL. Inclusion criteria consisted of histologically confirmed FeNL, available paraffin blocks of diagnostic quality, localised to the sinonasal cavity on staging pre-RT, treated with IMRT/IGRT (10 × 4.2 Gy) without chemotherapy and at least 1 year follow-up. All pre-RT biopsies were reviewed and evaluated with CD3, CD20, CD79a, pan-CK and Ki-67 immunohistochemistry and the mitotic activity index was determined. The primary endpoint was progression-free survival (PFS) at 1 year and hazard-ratios (HR) with confidence interval (CI) were calculated. Twenty-eight cats fit the inclusion criteria, and all had diffuse large B-cell lymphoma. Seventeen cats (61%) were progression free at 1 year. Of the 11 cats that progressed in the first year, two had local progression, two had both local and systemic progression and seven had systemic progression. The mitotic index (HR: 1.03, CI 0.9-1.19, p = 0.645), Ki-67 (HR: 1.00, CI 0.98-1.02, p = 0.845) and > 30% of tumour-infiltrating T cells (HR: 0.38, CI 0.09-1.56, p = 0.175) were not significantly associated with PFS. In this uniformly RT treated population of FeNL, none of the evaluated pre-RT histologic parameters could predict early treatment failure.

Keywords: IMRT; KI‐67; cats; lymphoma; treatment failure; tumour‐infiltrating lymphocytes.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Cat selection algorithm. DLBCL, Diffuse large B‐cell lymphoma; FeNL, Feline nasal lymphoma; H&E, Haematoxylin and eosin; IHC, Immunohistochemistry; IMRT, Intensity‐modulated radiation therapy; MALT, Mucosa‐associated lymphoid tissue; OVC, Ontario Veterinary College; SASH, Small Animal Specialty Hospital; UW, University of Wisconsin; UZH, Vetsuisse Faculty Zurich.
FIGURE 2
FIGURE 2
Histological and immunohistochemical characteristics of feline nasal lymphoma. (A) and (B) Low‐power appearance of diffuse large B‐cell lymphoma (asterisk) and normal mucosa with reactive lymphoid follicle (arrowhead). (A) haematoxylin and eosin, 4 × objective. (B) CD20 IHC with haematoxylin counterstain, 4 × objective. (C) High‐power magnification immunoblastic cells and atypical mitotic figure, haematoxylin and eosin, 40 × objective. (D) 80%–90% of lymphocytes are positive for Ki‐67, Ki‐67 IHC with haematoxylin counterstain, 40 × objective. (E) Areas of necrosis, haematoxylin counterstain, 20 × objective. (F) Epitheliotropic B cells (asterisk) invading the overlying epithelium, CD20 IHC with haematoxylin counterstain, 20 × objective.
FIGURE 3
FIGURE 3
Progression‐free survival with a 95% confidence interval for all cats (A) without stratification and (B) stratified by the percentage of tumour‐infiltrating T cells. Tick marks represent censored patients.
See this image and copyright information in PMC

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