Outcome and failure patterns of localized sinonasal lymphoma in cats treated with first‐line single‐modality radiation therapy: A retrospective study

Failure rate and site are not well defined in localized sinonasal lymphoma in cats treated with radiotherapy. In this study, we describe (a) failure pattern, (b) outcome, (c) influence of previously reported prognostic variables on the outcome in cats with suspected localized sinonasal lymphoma. In this multi‐institutional retrospective study, we included 51 cats treated with single‐modality radiotherapy. Cats were irradiated using 10x4.2Gy (n = 32), 12x3Gy (n = 11) or 5x6Gy (n = 8). Regional lymph nodes were prophylactically irradiated in 24/51 cats (47.1%). Twenty‐five cats (49.0%) developed progressive disease: progression was local (nasal) in five (9.8%), locoregional (nodal) in two (3.9%), local and locoregional in three (5.9%), systemic in nine (17.6%) and both local and systemic in six cats (11.8%). No cat receiving prophylactic nodal irradiation had progression in the locoregional lymph nodes. The median time to progression was 974 days (95%CI: 283;1666), with 58% and 53% of cats free of progression at 1 and 2 years, respectively. Median overall survival was 922 days (95%CI: 66;1779) with 61% and 49% alive at 1 and 2 years, respectively. Half of the cats that died of relapse/progression (13/26) died within 6 months of treatment, suggesting possible shortcomings of staging, rapid dissemination of disease or sequential lymphomagenesis. None of the prognostic factors evaluated were predictive of outcome (prednisolone use, anaemia, nasopharyngeal involvement, modified canine Adams tumour stage, protocol, total dose). Radiotherapy is an effective treatment for localized sinonasal lymphoma with a long time to progression. However, in one‐third of the cats, systemic disease progression occurs soon after radiotherapy.     

Survival Analysis of 97 Cats with Nasal Lymphoma: A Multi-Institutional Retrospective Study (1986–2006)

Background: Feline nasal lymphoma (NLSA) is a condition for which no standard of care exists.
Hypothesis: There is no difference in survival times of cats with NLSA treated with single or multimodality therapy.
Animals: Records from 97 cats diagnosed with NLSA were examined.
Methods: The purpose of this retrospective study was to compare the survival times of cats with NLSA treated with radiation therapy (RT) alone, chemotherapy alone, or RT + chemotherapy and identify potential prognostic variables that affected survival. Cats were grouped according to therapy: RT + chemotherapy (n = 60), RT alone (n = 19), or chemotherapy alone (n = 18).
Results: Survival was calculated with 2 methods. The 1st survival analysis (method A) included all cats, but counted only deaths caused by progressive NLSA. The median survival time (MST), regardless of therapy modality, was 536 days. The 2nd survival analysis (method B) also included all cats and counted all deaths, regardless of cause, as events. The overall MST calculated for all deaths was 172 days. A negative independent prognostic variable identified was anemia ( P < .001), and positive independent prognostic variables were a complete response to therapy ( P < .001) and total radiation dose >32 Gy ( P = .03).
Conclusions and Clinical Importance: There were no significant differences in survival times among the 3 treatment groups but these results suggest that the addition of higher doses of RT to a cat's treatment protocol may control local disease and therefore influence survival.     

Hypofractionated radiation therapy of oral melanoma in five cats

Five cats with melanoma involving the oral cavity were treated with hypofractionated radiation therapy (RT). Cobalt photons were used to administer three fractions of 8.0 Gray (Gy) for a total dose of 24 Gy. Four cats received radiation on days 0, 7, and 21 and one cat received radiation on days 0, 7, and 13. One of the cats received additional irradiation following the initial treatment course. Two cats received chemotherapy. Their age ranged from 11 to 15 years with a median age of 12 years. Three cats had a response to radiation, including one complete response and two partial responses. All five cats were euthanized due to progression of disease, with one cat having evidence of metastatic disease at the time of euthanasia. The median survival time for the five cats was 146 days (range 66-224 days) from the start of RT. The results of this study suggest that oral melanoma in cats may be responsive to hypofractionated RT, but response does not seem to be durable.     

EFFICACY AND TOXICITY OF AN ACCELERATED HYPOFRACTIONATED RADIATION THERAPY PROTOCOL IN CATS WITH ORAL SQUAMOUS CELL CARCINOMA

Squamous cell carcinoma (SCC) is the most common feline oral tumor. Standard radiation protocols have been reported to achieve tumor control durations of 1.5–5.5 months (45–165 days). The purpose of this study was to describe the efficacy and toxicity of an accelerated hypofractionated radiation therapy protocol in cats with oral SCC. Twenty‐one cats with histologically confirmed oral SCC and T1‐3N0M0 were treated with 10 once‐daily fractions (Monday–Friday) of 4.8 Gy. Seventeen cats had macroscopic disease and four were microscopic after incomplete excision. Acute toxicity consisted of grade 2 mucositis in all cats and this was effectively managed using esophageal or gastric tube feeding, pain medication, and antibiotics. Late toxicity effects for cats with available follow‐up data included alopecia (4 cats), leukotricia (6), tongue ulceration (1), and oronasal fistula (1). Response could be assessed in 17 cats (seven complete response and five partial response). Four cats (19%) developed metastatic disease without evidence of local progression. The median progression‐free survival (PFS) was 105 days (1 year PFS of 23%), median local progression‐free survival (LPFS) was 219 days (1 year LPFS of 41%), and median overall survival (OS) was 174 days (1 year OS of 29%). Only tumor stage was prognostic, with T1 having a median PFS of 590 days. Findings indicated that this accelerated hypofractionated radiation therapy protocol was well tolerated in cats with oral SCC, with manageable adverse events. Tumor response was observed in most cats and long tumor control durations were achieved in some cats.     

Outcome of stereotactic body radiation for treatment of nasal and nasopharyngeal lymphoma in 32 cats

BackgroundThe safety and efficacy of stereotactic body radiation therapy (SBRT) in the treatment of localized nasal lymphoma in cats has not been described.HypothesisStereotactic body radiation therapy with or without adjuvant chemotherapy is an effective and well‐tolerated treatment for localized nasal lymphoma in cats.AnimalsThirty‐two client owned cats referred to Colorado State University for the treatment of nasal lymphoma.MethodsRetrospective study of cats treated with SBRT between 2010 and 2020 at Colorado State University. Diagnosis of nasal lymphoma was obtained via cytology or histopathology. Signalment, radiation protocol, concurrent treatments, adverse effects, and survival were recorded.ResultsProgression free survival was 225 days (95% CI 98–514) and median survival time (MST) was 365 days (95% CI 123–531). No significant difference in survival was identified between cats that received 1 versus greater than 1 fraction (MST 427 vs. 123 days, P = 0.88). Negative prognostic factors included cribriform lysis (MST 121 vs. 876 days, P = 0.0009) and intracalvarial involvement (MST 100 vs. 438 days, P = 0.0007). Disease progression was noted in 38% (12/32), locally in 22% (7/32), and systemically in 16% (5/32). No cats developed acute adverse effects. Ten cats developed late adverse effects: keratitis/keratitis sicca (n = 2), alopecia (n = 4), and leukotrichia (n = 4). Twenty‐four cats (75%) had signs consistent with chronic rhinitis.ConclusionsSBRT is effective and well tolerated for treating localized nasal lymphoma in cats. Outcomes for cats with lower stage disease (canine modified Adam''s stage 3 and lower) are comparable to historic data of cats treated with fractionated radiation therapy.     

CHEMOTHERAPY FOLLOWED BY ABDOMINAL CAVITY IRRADIATION FOR FELINE LYMPHOBLASTIC LYMPHOMA

Combination chemotherapy is standard care for feline lymphoma, although clinically relevant improvements in remission duration are unlikely to result from manipulations of chemotherapy agents alone. Lymphopoietic tissues generally are sensitive to radiation, and support for chemoradiotherapy as a treatment for lymphoma is found in both humans and dogs. The goal of this prospective pilot study was to determine the normal tissue tolerance to 15 Gy total abdomen fractionated radiation therapy following induction chemotherapy in cats with lymphoblastic lymphoma. Eight cats with lymphoblastic gastrointestinal or multicentric lymphoma confined to the abdominal cavity were treated with a 6‐week combination chemotherapy protocol followed 2 weeks later by whole‐abdomen radiation therapy consisting of 10 daily fractions of 1.5 Gy. Treatment was well tolerated; renal insufficiency documented in one cat at the start of radiation therapy progressed to stable chronic renal failure. One cat not in complete remission at the time of radiation therapy relapsed 2 weeks later, one cat with multicentric lymphoma relapsed with hepatic large granular lymphoma, and one cat was euthanatized 3 weeks following completion of radiation therapy for other reasons; no evidence of lymphoma or radiation toxicoses was identified on post mortem evaluation. The remaining five cats remain in remission at least 266 days after starting therapy; median remission duration has not been reached (range, >266 to >1332 days). Results of this study suggest that 15 Gy total abdomen fractionated radiation therapy after induction chemotherapy is tolerated satisfactorily. This protocol is suitable for further testing to quantify efficacy.     

RADIOTHERAPY OF FELINE NASAL TUMORS A Retrospective Study of Nine Cases

Between 1978 and 1986, nine cats with nasal tumors were treated with radiation therapy. Rhinotomy was performed in six cats and diagnostic biopsy procedures were performed in three cats. For four of the specimens, a histologic review was significantly different from the initial diagnosis. At the time of analysis, one cat was alive and disease free 26.3 months after the first radiation therapy treatment; two of the cats were dead as a result of local recurrence, four were dead because of unrelated causes, and two were dead of unknown causes. The mean and median survival of cats in this study were 27.9 and 20.8 months, respectively, following the first radiation therapy. There was a 66.7% one-year, 44% two-year, and 33% three-year survival rate. Complications of the surgery and radiation therapy were minimal. In conclusion, the histologic evaluation of nasal neoplasms in cats is not straightforward and may require specialized histologic technics for accurate diagnosis. Radiation appears to be safe and may be efficacious in local control of feline nasal tumors.     

RESPONSE OF FELINE ORAL SQUAMOUS CELL CARCINOMA TO PALLIATIVE RADIATION THERAPY

Seven cats with advanced oral squamous cell carcinoma were treated with palliative radiotherapy. Megavoltage radiation in 8 Gray (Gy) fractions was delivered on days 0, 7, and 21 for a total dose of 24 Gy. Treatment field included the mandible, oropharynx, retropharyngeal lymph nodes, and tonsils. Adjuvant treatment with chemotherapy was variable. Age ranged from 13 to 18 years old with a median age of 15 years. Three of the seven cats (43%) did not complete treatment. Six cats were euthanized due to tumor growth and/or radiation side effects with a median survival time of 60 days (range = 42 to 97 days, mean = 63 +/- 8.4 days). Radiotherapy complications or progression of disease occurred in 6 of 7 (85.7 %) cats and included adverse clinical signs, such as mucositis, serosanguinous oral discharge, pain, and dysphagia. These data suggest that coarse fractionation radiotherapy did not result in palliation in cats with inoperable oral squamous cell carcinoma.     

Coarse Fractionated Radiation Therapy for Pituitary Tumours in Cats: A Retrospective Study of 10 Cases

Introduction:  Pituitary tumours are uncommon in cats. Signs may be due to either an expansile mass or paraneoplastic effects (acromegaly and/or unstable diabetes mellitus). There are a few small case series providing evidence of efficacy for radiotherapy of pituitary tumours in cats. This retrospective study describes the outcome of ten cats with pituitary tumours treated with course‐fractionated radiation.
Methods:  The medical records of cats with MRI‐confirmed pituitary tumours that underwent radiotherapy were reviewed. A standard coarse‐fractioned radiation protocol was used; 37 Gy in 5 once‐weekly fractions using two parallel‐opposed 4MeV X‐ray beams. Survival times were calculated from date of first radiation dose.
Results:  Ten cats with pituitary tumours underwent radiotherapy. 5 cats had CNS signs and 5 had evidence of growth hormone excess (1 cat also showed CNS signs). 2 cats with pre‐existing moderate to severe CNS signs died of unknown causes before completing the radiation course. Of the remaining 4 with CNS signs, 3 had complete resolution of signs and the fourth showed partial improvement. Of the 5 cats with unstable diabetes, 2 no longer required insulin and 3 became stable at a lowered dose. The median survival time was 77.6 weeks. 6 cats died: 2 without completing the radiation course, 2 from unrelated causes (CRF, VAFS) and 2 from relapse and/or progression of CNS signs. 4 cats remain alive (range 34–191 weeks).
Conclusions:  Radiation therapy is confirmed as an effective treatment for pituitary tumours in cats giving extended survival and control of both direct mass effect and paraneoplastic signs.     

A Comparison of Doxorubicin and COP for Maintenance of Remission in Cats With Lymphoma

Thirty-eight cats with lymphoma were treated with vincristine, cyclophosphamide, and prednisone (COP). They were randomized at entry to receive maintenance chemotherapy consisting of either single-agent doxorubicin or continued COP therapy, starting on week 4 of treatment and continuing for 6 months or until relapse. Eighteen cats achieved complete clinical remission after COP induction chemotherapy. The median remission duration for 11 cats continuing to receive COP was 83 days, which was significantly shorter than for 7 cats that received doxorubicin (281 days). Thus, doxorubicin should be considered a well-tolerated and efficacious agent for the maintenance of remission in cats with lymphoma.     

CONCOMITANT LIPOSOMAL DOXORUBICIN AND DAILY PALLIATIVE RADIOTHERAPY IN ADVANCED FELINE SOFT TISSUE SARCOMAS

Local recurrence of feline soft tissue sarcomas is common despite aggressive treatment. Liposomal doxorubicin might serve as a depot radiosensitizer if administered concomitantly with daily radiotherapy and thus improve tumor control. In this pilot study, the feasibility of concomitant liposomal radiochemotherapy was evaluated in a palliative setting in 10 cats with advanced soft tissue sarcomas. Cats were treated with median number of 5 (range 5–7) daily fractions of radiotherapy and a median total dose of 20 Gy (range 20–31.5 Gy). One dose of liposomal doxorubicin was administered at the beginning of radiotherapy. Seven cats received further free or liposomal doxorubicin after completion of the liposomal doxorubicin/radiation protocol. Seven of the treated 10 cats (70%) achieved a partial (n=5) or complete (n=2) response with a median response duration of 237 days. The median progression free interval in all 10 cats was 117 days and the median overall survival time was 324 days. Concomitant liposomal radiochemotherapy was tolerated well in nine cats, one cat experienced temporary anorexia. Although the number of patients is too small to make definitive conclusions, results appear promising enough to investigate the role of liposomal doxorubicin as a radiosensitizer further.     

Hypofractionated radiation therapy for the treatment of malignant melanoma and squamous cell carcinoma in dogs and cats

This study describes the experience with hypofractionated radiation therapy of squamous cell carcinoma and melanoma in dogs and cats. A total dose of 32-48 Gray (Gy) was delivered once a week in 8 Gy fractions. 34 animals in which a complete surgical excision was impossible were treated. There was no tumor detectable macroscopically in 14 patients at the beginning of radiation therapy. In 20 animals the median volume of the tumor was 9.9 cm3. The median survival times and the local tumor control of squamous cell carcinoma of the oral and nasal cavities and of the body are comparable to results which were reached with a Monday-Wednesday-Friday scheme. For the treatment of Melanoma the hypofractionated radiation therapy is first choice. There are no significant side effects. Late side effects did not occur. 88% of the owners are satisfied with this kind of treatment and would choose it again.     

Hypofractionated radiation therapy for the treatment of microscopic canine soft tissue sarcoma

Soft tissue sarcomas (STSs) are locally invasive and surgery with or without radiation therapy is the current standard of care in dogs. Typical protocols for treating incompletely excised STSs involve curative intent radiation with total dose in excess of 50 Gy. Forty‐eight dogs with histologically confirmed incomplete or closely excised STSs were treated with a hypofractionated protocol that is typically reserved for palliative radiation therapy (RT) (6–8 Gy/weekly fractions to a total dose of 24–32 Gy). Ten dogs (21%) developed local recurrence, 11 dogs (23%) developed metastasis, and 3 dogs developed both (included in each group). The median progression free survival was 698 days. The local failure‐free probability at 1 and 3 years was 81 and 73%. The 1 and 3 years tumour‐specific overall survival was 81 and 61%. Long‐term local tumour control was achieved in the majority of dogs. This protocol is reasonable to prescribe in older patients or when financial limitations exist.     

PROTON SPOT SCANNING RADIOTHERAPY OF SPONTANEOUS CANINE TUMORS

Thirty dogs with spontaneous tumors were irradiated with proton therapy using a novel spot scanning technique to evaluate the safety and efficacy of the system, and to study the acute and late radiation reactions. Nasal tumors, soft tissue sarcomas, and miscellaneous tumors of the head were treated with a median total dose of 52.5 Gy given in 3.5 Gy fractions. Acute effects, late effects, tumor response, and outcome were analyzed. No unexpected radiation reactions were seen, however two dogs did develop in-field osteosarcoma, and one dog developed in-field bone necrosis. Complete response to therapy was seen in 40% (12/30), partial response in 47% (14/30), and no response in 13% (4/30). Median survival for all dogs was 385 days (range of 14–4583 days). Dogs with nasal cavity tumors had a median survival of 385 days (range of 131–1851 days) and dogs with soft tissue sarcomas had a median survival time of 612 days (range of 65–4588 days). Treatment outcome was similar to historical controls. This new proton spot scanning technique proved to be safe and reliable.     

Chemotherapy of lymphoma in 75 cats

Seventy-five cats with lymphoma were treated with combination sequential chemotherapy consisting of vincristine, cyclophosphamide, and methotrexate. Thirty-nine cats had mediastinal, 16 had multicentric, 14 had alimentary, and 6 had renal lymphoma. The median survival time of the 75 cats was 8 weeks, with a mean of 32 weeks. Sixty-two cats had follow-up evaluation until death or cure and had a median survival time of 7 weeks, with a mean of 37 weeks. Of the 62 cats, 32 (52%) attained complete remission, with a median remission duration of 16 weeks and a mean of 46 weeks. The addition of prednisolone and/or L-asparaginase to the protocol did not improve the results. Sixteen cats with multicentric lymphoma had the longest survival times (median, 18 months) and remission durations (median, 25 months). Prognostic factors were evaluated in each anatomic form of lymphoma.     

Chemotherapy with cyclophosphamide, vincristine, and prednisolone (COP) in cats with malignant lymphoma: new results with an old protocol

This retrospective study in 61 cats with malignant lymphomas examined the efficacy of a well-established chemotherapy protocol (cyclophosphamide, vincristine, and prednisolone [COP]) in the Netherlands, a country with a low prevalence of feline leukemia virus (FeLV). Twenty-two cats (36.1%) had mediastinal lymphoma, 11 (18.0%) had alimentary lymphoma, 7 (11.5%) had peripheral lymphoma, 8 (13.1%) had nasal lymphoma, and 13 (21.3%) had miscellaneous lymphoma (including renal lymphoma in 2 [3.3%]). Of the 54 cats that were tested, only 4 (7.4%) were FeLV positive. Complete remission (CR) was achieved in 46 of the 61 cats (75.4%). The estimated 1- and 2-year disease-free periods (DFPs) in the 46 cats with CR were 51.4 and 37.8%, respectively, whereas the median duration of remission was 251 days. The overall estimated 1-year survival rate in all cats was 48.7%, and the 2-year survival rate was 39.9%, with a median survival of 266 days. The median survival time and the 1-year survival rate for mediastinal lymphoma were 262 days and 49.4%. respectively. Siamese cats had a more favorable prognosis for survival and remission than other breeds. Response to therapy in this study was shown to be a significant prognostic indicator. CR is necessary for long-term survival. Cats that did not achieve CR had little chance of survival for longer than I year. Young Siamese cats in this study had a greater tendency to develop mediastinal malignant lymphoma at a young age, and all were FeLV negative. In comparison with results reported in other studies with different combination chemotherapy protocols, these are among the highest percentages of remission and the longest survival rates for cats with malignant lymphoma.     

RADIOTHERAPY AND SURGERY FOR FELINE SOFT TISSUE SARCOMA

Medical records for 79 cats with soft tissue sarcomas treated with preoperative or postoperative curative intent radiation therapy between August 1994 and February 2004 were reviewed. The purpose was to assess the effectiveness of preoperative and postoperative radiation therapy, and to determine the association of patient and radiation treatment variables with survival. Gender, age, weight, anatomic tumor site, packed cell volume (PCV), computerized vs. manual treatment planning, radiation field length, preoperative vs. postoperative irradiation, total radiation dose, and biologically effective dose (BED) were assessed as prognostic factors for survival. Fifty-six of 79 (71%) of cats were anemic within 2 weeks before or during radiation treatment. The median survival was 520 days for all cats, with a 1-year survival rate of 61.6%, and a 2-year survival rate of 41.6%. Only timing of radiation therapy relative to surgery and presence of a moderate or severe anemia were significantly related to survival. The median survival was 310 days for cats treated with preoperative radiation therapy, and 705 days for cats treated with postoperative radiation therapy ( P =0.03). The median survival was 308 days for cats with a PCV<25%, and 760 days for cats with a PCV≥25% ( P =0.017). Radiation therapy in combination with surgery results in relatively long-term survival in cats with soft tissue sarcomas. Anemia is common in cats undergoing radiation therapy for soft tissue sarcomas, and is associated with decreased survival.     

Feline extranodal lymphoma: response to chemotherapy and survival in 110 cats

O bjective : To determine response to treatment, survival and prognostic factors for feline extranodal lymphoma in the UK.
M ethods : Records of cats diagnosed with lymphoma of extranodal sites at seven referral centres were reviewed and information on signalment, tumour location, prior treatment and chemotherapy protocol recorded. Factors influencing response to treatment and survival were assessed.
R esults : One hundred and forty-nine cases met inclusion criteria. Sixty-nine cats had nasal lymphoma, 35 renal, 15 central nervous system, 11 laryngeal and 19 miscellaneous locations. Sixty-six cats received cyclophosphamide, vincristine, prednisolone, 25 Wisconsin-Madison doxorubicin-containing multi-agent protocol, 10 prednisolone alone and nine other combinations. The response rate for the 110 treated cats was 85·5 per cent. Of cyclophosphamide, vincristine, prednisolone treated cats 72·7 per cent achieved complete remission, median survival 239 days. Sixty-four per cent of Wisconsin-Madison treated cats achieved complete remission, median survival 563 days. Cats with nasal lymphoma achieving complete remission had the longest survival (749 days) and cats with central nervous system lymphoma the shortest (70 days). If complete remission was achieved, prior treatment with corticosteroids significantly reduced survival time.
C linical S ignificance : Cats with extranodal lymphoma respond to chemotherapy and achieve survival times comparable to other locations. Corticosteroid pretreatment reduced survival time in cats achieving complete remission.     

AN ACCELERATED TECHNIQUE FOR IRRADIATION OF MALIGNANT CANINE NASAL AND PARANASAL SINUS TUMORS

Tumor and normal tissue response was assessed in 21 dogs with malignant nasal tumors given 42 Gy cobalt radiation in 9 or 10 fractions over 11 to 13 days. Local tumor/clinical relapse recurred in 68% of dogs, with a median relapse free interval (RFI) of 270 days. Median survival was 428 days. One year survival for all dogs was 60%. RFI and survival times are better than, or similar to, previous reports of dogs treated with radiotherapy only. Acute radiation effects were severe in one dog. Late effects were severe in six of 15 dogs (40%) with durable tumor control. Late effects included bilateral blindness (3), osteoradionecrosis (3), and seizures (1). These six dogs had a median survival of 705 days. Loss of vision occurred in at least one eye in nine dogs (47%). Tumor staging based on CT findings were predictive for survival duration. Tumor histology was not predictive of outcome. Labrador Retrievers were significantly over-represented. Despite comparable or improved tumor control and survival times provided by this accelerated protocol, relative to other radiotherapy reports, local failure remains the major cause of death, and late radiation effects can be severe in dogs with durable tumor control.     

A retrospective evaluation of lomustine (CeeNU) in 32 treatment naïve cats with intermediate to large cell gastrointestinal lymphoma (2006–2013)

Multi‐drug chemotherapy protocols for feline lymphoma have demonstrated variable efficacy and tolerability. In phase I trials, lomustine has demonstrated efficacy for cats with lymphoma though its use for treatment naïve feline intermediate/large cell gastrointestinal (GI) lymphoma remains unknown. This study evaluated the efficacy and tolerability of lomustine for the treatment of feline GI lymphoma. Thirty‐two cats with histologically or cytologically confirmed intermediate/large cell GI lymphoma were evaluated retrospectively. Factors assessed included clinical signs, hematologic/biochemical parameters and use of l ‐asparaginase at induction. A response rate of 50% (16/32), with median duration of response of 302 days (range 64–1450 days), was found. Median progression‐free interval was 132 days (range 31–1450 days), with overall median survival time of 108 days (range 4–1488 days). History of hyporexia, presence of anaemia and dose of lomustine were significantly associated with progression‐free survival. Overall, lomustine is a well‐tolerated and effective treatment for feline GI lymphoma.