Received dose variability after administration of I-131 for treatment of hyperthyroidism in cats

Abstract Background Injectable radioactive iodine (I‐131) frequently is used to treat hyperthyroidism in cats. In human medicine, residual activity after injection of radionuclides has been reported, and the actual quantity administered is recorded after administration. Objective Our aim was to evaluate actual administered dose variability after administration of preprepared I‐131 single unit doses for the treatment of hyperthyroidism in cats. Animals Twenty‐seven cats with hyperthyroidism treated with I‐131 between April 2017 and March 2019. Methods Retrospective observational study of cats treated with preprepared single unit I‐131 doses. For each dose, the measured activity before administration and residual activity were recorded. The measured dose and the actual dose administered were compared to the prescribed dose. Results Measured activity before administration ranged from 88.4% to 103.3% of the prescribed dose. Mean residual activity was 5.2 ± 3.0 MBq (ranging from 1.5% to 15% of the prescribed dose). The actual dose administered (measured activity − residual activity) ranged from 79.1% to 100.2% of the prescribed dose. Seventeen of 28 (60.7%) of the actual administered doses differed between 10% and 20% of the prescribed dose. One administered dose had a >20% difference compared to the prescribed dose (79.10% of the prescribed dose). Conclusion and Clinical Importance Our study identified variability in the residual and actual administered activity of I‐131 as compared to the prescribed dose, which should be taken into consideration when treating cats with (predrawn) I‐131

Definitive-intent radiotherapy for sinonasal carcinoma in cats: a multicenter retrospective assessment

Treatment of epithelial sinonasal tumors in cats is not commonly reported. Palliative radiation protocols have been described more often than definitive-intent protocols. In this multi-institutional retrospective study, we included 27 cats treated with single-modality radiotherapy. Cats were irradiated using 10 daily fractions of 4.2Gy. Three cats (11.1%) experienced a complete clinical response and 17 (63%) had a partial clinical response. Stable clinical disease was noted in three cats (11.1%). Four cats (14.8%) showed progression within 3 months following treatment. The median time to progression for all cases was 269 days (95% CI: 225;314). The proportion of cats free of progression at 1 and 2 years was 24% (95%CI: 22%;26%) and 5% (95%CI: 5%;6%), respectively. None of the prognostic factors evaluated were predictive of outcome (anemia, tumor volume at the time of staging, modified Adams stage, intracranial involvement, facial deformity, epistaxis, inappetence or weight loss). Median overall survival (OS) for all deaths was 452 days (95%CI: 334;571). The proportion of cats alive at 1 and 2 years was 57% (95%CI: 37%;77%) and 27% (95%CI: 25%;29%), respectively. Surprisingly, cats with epistaxis had a longer median OS of 828 days (95%CI: 356;1301) compared to 296 days (95%CI: 85;508) in cats without epistaxis, (p=0.04, Breslow). Radiation therapy used as a single modality for the treatment of feline sinonasal carcinoma improved clinical signs and was well tolerated

Efficacy of radiation therapy for the treatment of macroscopic canine oral soft tissue sarcoma

This retrospective study evaluated the efficacy of radiotherapy used alone in macroscopic oral soft tissue sarcoma. Thirty-one dogs qualified for the study. Twenty dogs received curative radiotherapy (median total dose: 52.5 Gy) and eleven dogs were treated palliatively (3 x 8 Gy or 5 x 6 Gy). The time-to-progression for the curatively-treated dogs was 333 days versus 180 days for the palliatively-treated dogs (p=0.134). The overall survival was 331 days for the curative group and 310 days for the palliative group (p =0.2292). The results of this study suggest that radiation therapy is useful in the treatment of oral soft tissue sarcoma

Reason for euthanasia in dogs with urothelial carcinoma treated with chemotherapy or radiation therapy or both: A retrospective observational study

Abstract Background Clients want to know the ultimate cause of death in their pet after cancer treatment. The cause of euthanasia and investigation of urinary obstruction in treated dogs with urothelial carcinoma (UC) has not been specifically reported in veterinary literature. Hypothesis/Objectives Our hypothesis was that the majority of treated dogs with UC are euthanized secondary to primary tumor factors, such as urinary obstruction. Animals Fifty‐nine client‐owned dogs diagnosed with UC. Methods Retrospective observational study on clinical signs and disease at euthanasia of dogs with UC treated by radiation therapy or chemotherapy or both. Results The median overall survival time (OST) of all dogs was 339 days (range, 17‐1996; 95% confidence interval [CI], 185‐392; interquartile range [IQR], 112‐505). Of dogs deemed to have been euthanized because of UC (50/59, 85%), the primary cause was considered to be local progression in 31/50 (62%), most often because of perceived complete or partial urinary obstruction (24/31, 77%). No variables were found to be predictive of urinary obstruction. The overall documented metastatic rate was 56%. In dogs euthanized because of UC, metastasis was deemed to be the cause in 19/50 (38%) dogs. Conclusions and Clinical Importance Regardless of the type of treatment, UC in dogs has a poor prognosis and there is a continuing need to improve treatments that focus on local control of the primary tumor, given its high contribution to the decision for euthanasia. Proactive management to avoid the high frequency of urinary obstruction may be worthy of future investigation

Definitive‐intent intensity‐modulated radiation therapy provides similar outcomes to those previously published for definitive‐intent three‐dimensional conformal radiation therapy in dogs with primary brain tumors: A multi‐institutional retrospective study

Radiotherapy with or without surgery is a common choice for brain tumors in dogs. Although numerous studies have evaluated use of three-dimensional conformal radiotherapy, reports of definitive-intent, intensity modulated radiation therapy (IMRT) for canine intracranial tumors are lacking. IMRT has the benefit of decreasing dose to nearby organs at risk and may aid in reducing toxicity. However, increasing dose conformity with IMRT calls for accurate target delineation and daily patient positioning, in order to decrease the risk of a geographic miss. To determine survival outcome and toxicity, we performed a multi-institutional retrospective evaluation of dogs with brain tumors treated with IMRT. Fifty-two dogs treated with fractionated, definitive-intent IMRT at four academic radiotherapy facilities were included. All dogs presented with neurologic signs and were diagnosed via magnetic resonance imaging. Presumed radiological diagnoses included 37 meningiomas, 12 gliomas, and 1 peripheral nerve sheath tumor. One dog had two presumed meningiomas and one dog had either a glioma or meningioma. All dogs were treated in the macroscopic disease setting and were prescribed a total dose of 45-50 Gy (2.25-2.5 Gy per fraction in 18-20 daily fractions). Median survival time for all patients, including seven cases treated with a second course of therapy was 18.1 months (95% CI 12.3-26.6 months). As previously described for brain tumors, increasing severity of neurologic signs at diagnosis was associated with a worse outcome. IMRT was well tolerated with few reported acute, acute delayed or late side effects

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

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

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