Dosimetric benefit of adaptive radiotherapy in the neoadjuvant management of canine and feline thymoma—An exploratory case series

Bley, Carla Rohrer; Meier, Valeria; Schneider, Uwe

doi:10.1111/vco.12382

Cited by 12 publications

(14 citation statements)

References 22 publications

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“…In the case of large or incompletely excised tumors, radiation therapy and/or chemotherapy may be performed in an adjuvant setting. Thymoma is considered a radiosensitive tumor, especially the lymphocyte-rich subtype [ 33 ], and different protocols have been proposed [ 33 , 37 , 38 , 39 ]. RT has been proposed as a monotherapy with a palliative intent in inoperable tumors.…”

Section: Discussionmentioning

confidence: 99%

Canine Epithelial Thymic Tumors: Outcome in 28 Dogs Treated by Surgery

Martano

Buracco

Morello

2021

Animals

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Thymoma is a tumor rarely reported in dogs and should be differentiated from mediastinal lymphoma. Clinical signs may have a late onset, and thymoma is often diagnosed when symptoms related to the space-occupying effect or paraneoplastic syndromes occur. CT and fine-needle aspirates or core biopsies are helpful in differential diagnosis, but flow cytometry may improve the pre-operative diagnostic ability. Concurrent paraneoplastic syndromes such as myasthenia gravis and hypercalcemia have been reported; however, their role as prognostic factors is not well determined. Surgical excision is the treatment of choice; adjuvant radiotherapy and/or chemotherapy may prolong survival in cases of incomplete excision or when a thymic carcinoma is diagnosed. Local recurrence and metastasis are infrequently reported; therefore, a long survival time is expected if the tumor is completely excised or if adjuvant therapy is undertaken. This article reports the authors’ experience with 28 dogs affected by 18 thymomas and 10 thymic carcinomas. The median overall survival in this series was 1173 days, and the median disease-free interval was 903 days. Dogs with thymic carcinoma had significantly shorter disease-free intervals and shorter, although not statistically significant, survival times. Dogs with Masaoka Stage III tumors had worse outcomes.

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Section: Discussionmentioning

confidence: 99%

Canine Epithelial Thymic Tumors: Outcome in 28 Dogs Treated by Surgery

Martano

Buracco

Morello

2021

Animals

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“…In one retrospective study in the dog, only seven of 17 mediastinal masses could be definitively diagnosed by cytology (16) and this appears likely in cats as well. In contrast, the two diseases tend to exhibit a different prognosis and to benefit from different therapeutic approach, with chemotherapy the preferred option for lymphoma while surgery and/or radiotherapy are often suggested for thymoma (17,18). Histopathologic biopsy may help to reach a definitive diagnosis but tru-cut biopsy, which is the easiest technique to sample mediastinal masses, may sometimes provide inconclusive results while surgical biopsies are often considered invasive procedures.…”

Section: Discussionmentioning

confidence: 99%

Flow Cytometric Analysis of Mediastinal Masses in Cats: A Retrospective Study

Bernardi

Martini

Perfetto³

et al. 2020

Front. Vet. Sci.

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Mediastinal masses occur in dogs and cats and are often investigated with cytology. However, discrimination between the two most common lesions (thymoma and lymphoma) may be challenging, especially when small/medium lymphocytes represent the prevalent population. The aim of the present study is to describe the flow cytometric aspects of mediastinal masses in cats and to assess the ability of flow cytometry (FC) to differentiate lymphoma from non-lymphomatous lesions. We retrospectively describe FC features of fine needle aspiration cytology from cats with mediastinal masses. Cases were grouped in lymphoma and non-lymphoma based on results of cytology, histopathology, PCR for antigen receptor rearrangement (PARR), clinical presentation, and follow-up. Scatter properties, positivities to CD5, CD4, CD8, CD21, CD18, and their co-expressions were recorded using a multicolour approach. Twenty cats were included, 12 lymphomas and eight non-lymphomatous cases. Forward scatter (FSC) of lymphoid cells was higher in the lymphoma group. Double positive CD4+CD8+ T-cells were the dominant population in eight out of 12 lymphomas, whereas non-lymphomatous lesions showed no dominant lymphoid population in five out of eight cases. Unlike dogs, the high prevalence of CD4+CD8+ lymphomas in cats it makes difficult to differentiate lymphoma from non-lymphomatous lesions using FC alone. FC may add interesting information to refine diagnosis in some cases, but PARR and histopathology remain mandatory to solve differential in case of expansion of small-medium sized double positive lymphoid cells.

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“…Lymphocytes are considered to be the most radiosensitive cell type within the body; this extreme radiosensitivity is due to immediate radiation‐induced apoptotic cell death after exposure to ionising radiation 7 . The high lymphocyte population in thymic neoplasms are thought to contribute to their radiosresponsiveness 7,8 . In addition, the neoplastic population of thymic epithelial cells is considered radioresponsive as well; which has been demonstrated in mouse studies, further supporting the use of radiation therapy for treatment of thymic neoplasms 9 .…”

Section: Introductionmentioning

confidence: 95%

“…Reported median survival time for canine thymomas treated with a conventional radiation therapy protocol of 40–60 Gy in 20–30 fractions is 248 days 2 . One case series utilised either 3DCRT or IMRT 3 Gy × 12 fraction radiation protocol as an intended neoadjuvant therapy prior to surgery in two dogs with a reported survival time of 346 and 388 days 8 . Another study using hypofractionated 3DCRT radiation protocols administered a total of 48–49 Gy to the tumours in weekly fractions for 6–7 weeks; the median survival time for this group of dogs was not reached (range: 8–1128 days) 11 .…”

Section: Introductionmentioning

confidence: 99%

Outcomes of dogs with thymoma treated with intensity modulated stereotactic body radiation therapy or non‐modulated hypofractionated radiation therapy

Trageser

Martin

Hoaglund

et al. 2022

Vet Comparative Oncology

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Canine thymomas are routinely treated with radiotherapy (RT). In this study, we investigate the response and toxicity of canine thymoma treated with intensity‐modulated stereotactic body radiation therapy (SBRT) relative to dogs treated with hypofractionated non‐modulated radiation therapy (NMRT). A retrospective study was performed of dogs with thymoma treated with RT (total: n = 15; SBRT: n = 8, NMRT: n = 7). Tumour response was evaluated in six dogs (40%); following SBRT, three dogs (100%) experienced stable disease (SD); following NMRT, one dog (33%) had a PR, and two dogs (67%) had SD. Median PFS was 116 days (range 66–727 days) for the SBRT group and 134 days (range 10–405 days) for the NMRT group. The MST for the SBRT group was 250 days (range 1–727 days) and 155 days (range 10–405 days) for NMRT. Median disease‐specific survival was 250 days (range 1–727 days) for the SBRT group and 169 days (range 20–405 days) for the NMRT group. No significant differences in survival data were found between the treatment groups, however the results from the small number of dogs analysed are likely underpowered for statistical comparisons. Reported acute and late side effects were limited to the lungs and heart and were statistically significantly more common in the NMRT (71%) compared to the SBRT group (25%) (p = .04). We suggest similar treatment efficacy may be provided for canine thymoma treated with either approach, but SBRT could provide the clinical benefit of reduced incidence of radiation‐induced toxicity and completion of RT in a shorter time frame.

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Dosimetric benefit of adaptive radiotherapy in the neoadjuvant management of canine and feline thymoma—An exploratory case series

Cited by 12 publications

References 22 publications

Canine Epithelial Thymic Tumors: Outcome in 28 Dogs Treated by Surgery

Canine Epithelial Thymic Tumors: Outcome in 28 Dogs Treated by Surgery

Flow Cytometric Analysis of Mediastinal Masses in Cats: A Retrospective Study

Outcomes of dogs with thymoma treated with intensity modulated stereotactic body radiation therapy or non‐modulated hypofractionated radiation therapy

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