Feline Lymphoma: Patient Characteristics and Response Outcome of the COP-Protocol in Cats with Malignant Lymphoma in The Netherlands

Abstract

Feline lymphoma is currently less commonly associated with retrovirus infections as the feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). This is thought to have caused a shift in the distribution of anatomical subtypes and eventually have led to poorer treatment outcomes. The aim of this study was to evaluate whether this change was also notable in the Netherlands, a country historically known for its low prevalence of FeLV and FIV, and to determine its consequences on treatment response. A 10-year cohort of 174 cats with large cell lymphoma (110 treated) were included and compared to historical data from previously published reports in the Netherlands. Of the 90 cats screened, only one tested positive for FeLV and three for FIV. The most current cohort had an increased age (median 8.7 years) and fever Siamese cats (6.3%) compared to previous reports, with alimentary (24.5%) and nasopharyngeal lymphoma (22.7%) being the most common subtypes. Sixty-six of the one hundred and ten cats (60%) went into complete remission, (CR) resulting in a median disease-free period (DFP) of 763 days, with nasopharyngeal and mediastinal having the longest DFP. The median overall survival time was 274 days with an estimated 1-year survival of 41.3% and a 2-year survival of 34.6%, respectively. Patient characteristics of cats with malignant lymphoma in the Netherlands have changed over the years, but this cannot be explained by differences in FeLV/FIV prevalence. Although the overall response rate to therapy did not change over time, for some lymphoma subtypes, longer DFPs were observed compared to 30 years ago.

Description and Characterization of Different Types of Lymphoma in Cats in Hong Kong

“…The higher frequency of abdominal lymphoma, especially GI lymphoma observed in this study, is consistent with studies from the USA, the United Kingdom, and other European countries where there is a similar low prevalence of FeLV, and for the same reason, multicentric, mediastinal, and other forms of lymphoma are rarer [ 1 , 9 , 10 , 11 , 12 , 13 , 19 ]. Interestingly, a form of nodal lymphoma affecting the cervical region was the third type of the most common lymphoma in Hong Kong.…”

“…The findings of this study corroborate previous similar research conducted in other countries but also highlight some potential differences in lymphoma characteristics affecting cats in Hong Kong and possibly in other regions of Asia compared to Western countries. Sex predisposition to feline lymphoma is controversial with some studies showing no sex predisposition [ 4 , 24 ], while others suggest a possible increase in incidence in males compared to females [ 1 , 2 , 10 , 13 , 14 ]. In our study, more males were diagnosed with lymphoma compared to females.…”

“…With the widespread use of FeLV vaccination, FeLV-induced forms of lymphoma are now less common [ 4 , 7 , 10 ]. This leads to regional variability of anatomical presentations with gastrointestinal lymphoma being the most prevalent in countries with a low FeLV prevalence [ 4 , 12 , 13 , 14 ], and multicentric and mediastinal forms being more common in countries with a higher rate of FeLV infections [ 3 , 15 ]. Different forms and types of lymphoma have, however, been reported in countries with a relatively low prevalence of FeLV-infected cats such as Australia, Japan, the USA, and other European countries [ 2 , 5 , 16 , 17 , 18 ].…”