Nasal tumours in dogs: definitive vs hypofractionated/palliative radiotherapy — POSSIBLE

In dogs with nasal tumours, does a definitive daily-fraction radiation protocol prolong survival vs a hypofractionated palliative protocol, and at what toxicity cost?

Shelf #119 · gate-verified and approved by the developer

POSSIBLE: The retrospective comparisons point the same way — curative-intent, more fractionated radiation is associated with longer survival than palliative hypofractionated schedules — but no randomised or prospective fractionation trial exists, and treatment intent is confounded by stage, histology and case selection. In the only within-study three-way comparison (Sones 2013, intranasal sarcomas), median survival was 641 days with daily-fractionated, 347 days with Monday/Wednesday/Friday-fractionated and 305 days with palliative protocols (curative intent vs palliative, P = 0.032). The definitive-protocol benchmark series (Adams 2005; 10 fractions of 4.2 Gy on consecutive weekdays) gave a median survival of 19.7 months and 44% 2-year survival with radiotherapy alone. Within the palliative setting, however, Hayes 2025 found no survival advantage for 10 fractions over 6 fractions in nasal carcinoma once stage was taken into account, and modern hypofractionated quad-shot cycles (Cabral 2025) achieved a median survival of 296 days with mostly mild acute toxicity (conjunctivitis 33%, mucositis 7%, radiodermatitis 6%). The classic weekly hypofractionated series of four 9 Gy doses (Mellanby 2002, PMID: 12233825; cross-pointed, not carded) reported clinical improvement in 53 of 56 dogs, a median survival of 212 days after the final dose, mild acute side effects in the majority and rare late side effects. Toxicity is reported thinly and inconsistently across all series, so the toxicity cost of definitive protocols cannot be quantified from these records. Tier C (survival benefit claim). Drafted Nov 10, 2026 (VetMed build, topic #119); all figures from abstracts fetched and verified at drafting.

Sones 2013: in 86 dogs with intranasal sarcoma, daily-fractionated radiation was associated with median survival of 641 days vs 305 days for palliative protocols

Retrospective multicentre comparison (record's own wording: medical records retrospectively reviewed; publication types: Comparative Study, Multicenter Study, Clinical Trial)

Who: Dogs: 86 dogs with confirmed intranasal sarcoma treated with radiation therapy at multiple referral centres (1996–2011): chondrosarcoma n = 42, fibrosarcoma n = 12, osteosarcoma n = 6, undifferentiated sarcoma n = 22 (subtype counts as printed in the record). Three protocols compared: daily-fractionated radiation therapy, Monday/Wednesday/Friday-fractionated radiation therapy, and palliative radiation therapy (per-protocol group sizes not stated in the record's abstract).

Result: Overall median survival time was 444 days. By histology: chondrosarcoma 463 days, fibrosarcoma 379 days, osteosarcoma 624 days, undifferentiated sarcoma 344 days. By protocol: daily-fractionated 641 days, Monday/Wednesday/Friday-fractionated 347 days, palliative 305 days. A significant difference in survival was found for curative-intent vs palliative radiation therapy (P = 0.032) and for daily-fractionated vs Monday/Wednesday/Friday-fractionated therapy (P = 0.0134). The authors concluded the findings support curative-intent radiation therapy for intranasal sarcoma and that future prospective, randomized trials are needed for confirmation.

Watch out: Retrospective and non-randomised despite the 'Clinical Trial' publication type carried on the record: protocol intent was chosen case by case, so dogs receiving palliative protocols plausibly had more advanced disease or other constraints — the survival gap cannot be read as the causal effect of fractionation. Sarcomas only; carcinomas, the majority of canine nasal tumours, are not represented. No toxicity comparison is reported in the record's abstract.

Sones E et al. Survival times for canine intranasal sarcomas treated with radiation therapy: 86 cases (1996-2011). Veterinary Radiology & Ultrasound. 2013;54(2):194-201. PMID: 23278974. Registry ID: none in the record. MeSH: Animals · Chondrosarcoma/radiotherapy · Chondrosarcoma/veterinary · Combined Modality Therapy/veterinary · Dog Diseases/radiotherapy · Dogs · Dose Fractionation, Radiation · Drug Therapy/veterinary · Female · Fibrosarcoma/radiotherapy · Fibrosarcoma/veterinary · Male · Nose Neoplasms/radiotherapy · Nose Neoplasms/veterinary · Osteosarcoma/radiotherapy · Osteosarcoma/veterinary · Prognosis · Radiotherapy/veterinary · Retrospective Studies · Sarcoma/radiotherapy · Sarcoma/veterinary · Survival Analysis · Time Factors · Treatment Outcome

Hayes 2025: in palliative treatment of canine nasal carcinoma, 6 fractions of 6 Gy were not worse than 10 fractions of 4 Gy — fractionation was not independently associated with survival

Retrospective comparison (publication type: Comparative Study)

Who: Dogs: 41 dogs with nasal carcinoma treated palliatively at a single institution (University of Cambridge, 2015–2022). Group A n = 17: 40 Gy in ten 4 Gy fractions delivered Monday, Wednesday and Friday. Group B n = 24: 36 Gy in six 6 Gy fractions delivered Monday and Friday.

Result: Median survival time was 298 days (95% CI 163.54–432.45) in Group A and 375 days (95% CI 240.73–509.27) in Group B; progression-free survival was 173 days (95% CI 117.87–228.12) and 243 days (95% CI 138.42–347.58) respectively. Overall response rate was 100% (Group A) and 96% (Group B). Dogs with Adams stage 1 disease had the longest median overall survival (593 days) and progression-free survival (609 days). In a multivariate Cox regression model stratified for tumour stage, neither epistaxis nor treatment (6 vs 10 fractions) was independently associated with survival. The authors concluded that increasing fractionation may have a limited effect on survival outcome or toxicity in the palliative setting.

Watch out: Both arms are palliative-intent, so this record tests fractionation within palliation, not definitive vs palliative intent; it tempers but does not refute the Sones signal. Retrospective, single institution, 41 dogs; epistaxis at presentation was more frequent in Group B (20 of 24, 83%) than Group A (11 of 17, 65%).

Hayes A, Wong H, Preston A, Dobson J. A Single Institution Retrospective Comparison of Two Radiotherapy Protocols for the Palliative Treatment of Canine Nasal Carcinoma. Veterinary Radiology & Ultrasound. 2025;66(6):e70097. PMID: 41047698. Registry ID: none in the record. MeSH: Animals · Carcinoma/radiotherapy · Carcinoma/veterinary · Dog Diseases/mortality · Dog Diseases/radiotherapy · Dogs · Female · Male · Nose Neoplasms/radiotherapy · Nose Neoplasms/veterinary · Palliative Care/methods · Retrospective Studies · Treatment Outcome

Adams 2005: definitive-intent accelerated radiotherapy (10 × 4.2 Gy) alone gave median survival of 19.7 months and 44% 2-year survival in malignant intranasal neoplasia

Retrospective study (record's own design wording; publication type: Research Support, Non-U.S. Gov't)

Who: Dogs: 53 dogs with malignant intranasal neoplasia at a referral centre (University of Wisconsin, 1990–2002). All dogs received radiotherapy of 10 fractions of 4.2 Gy on consecutive weekdays; a surgery group (n = 13) underwent exenteration of the nasal cavity if follow-up computed tomography showed persistent or recurrent tumour, leaving 40 dogs treated with radiotherapy alone.

Result: Two- and 3-year survival rates were 44% and 24% respectively for the radiotherapy-only group and 69% and 58% for the radiotherapy-and-surgery group, and median survival for radiotherapy alone (19.7 months) was significantly shorter than for the surgery group. Rhinitis (9 vs 4 dogs) and osteomyelitis-osteonecrosis (4 vs 3 dogs) occurred significantly more frequently in the surgery group than in the radiotherapy-only group. Surgery-group perioperative complications included haemorrhage requiring transfusion (2 dogs) and subcutaneous emphysema (8 dogs). The authors concluded exenteration after radiotherapy may prolong survival but increases the risk of chronic complications.

Watch out: This record benchmarks a definitive fractionated protocol; its internal comparison is radiotherapy vs radiotherapy plus later exenteration surgery, not one fractionation schedule against another — and surgery was offered only to dogs with CT-detected persistent or recurrent tumour, a selected subgroup. The record's abstract prints the surgery-group median survival as '477 months', an evident misprint; that figure is not used on this card.

Adams WM et al. Outcome of accelerated radiotherapy alone or accelerated radiotherapy followed by exenteration of the nasal cavity in dogs with intranasal neoplasia: 53 cases (1990-2002). Journal of the American Veterinary Medical Association. 2005;227(6):936-41. PMID: 16190593. Registry ID: none in the record. MeSH: Animals · Combined Modality Therapy/veterinary · Dog Diseases/radiotherapy · Dog Diseases/surgery · Dogs · Female · Male · Neoplasm Recurrence, Local/veterinary · Nose Neoplasms/radiotherapy · Nose Neoplasms/surgery · Nose Neoplasms/veterinary · Postoperative Complications/veterinary · Retrospective Studies · Survival Analysis · Tomography, X-Ray Computed/veterinary · Treatment Outcome

Cabral 2025: hypofractionated 'quad-shot' cycles gave median survival of 296 days with mostly mild acute toxicity in 81 dogs with sinonasal tumours

Retrospective study (record's own wording; no publication types listed on the record)

Who: Dogs: 81 dogs with sinonasal tumours treated at referral centres (2011–2023) with a palliative-intent cyclical hypofractionated protocol: cycles of four fractions of 3.25–4.0 Gy delivered over 48–72 hours, repeated every 3–4 weeks up to three cycles (maximum cumulative dose 48 Gy), mostly 3D conformal radiotherapy. Carcinomas accounted for 78% of cases; modified Adams stage 1 n = 5 (6%), stage 2 n = 8 (10%), stage 3 n = 29 (36%), stage 4 n = 33 (41%), unknown n = 6 (7%).

Result: Ninety percent of patients received three full cycles to a total of 39–48 Gy, and 77% showed clinical improvement at presentation for cycle 2 and 90% at presentation for cycle 3. Median progression-free interval was 207 days (95% CI 124–290) and median overall survival time 296 days (95% CI 177–415); 1-, 2- and 3-year survival rates were 40.6%, 17.2% and 9.4%. Acute toxicity was generally mild, with conjunctivitis (33%), mucositis (7%) and radiodermatitis (6%) most frequent; severe late toxicity was infrequent. In multivariable analysis, receiving three cycles (vs 1 or 2) was a positive prognostic factor. The authors concluded survival outcomes were comparable to other palliative radiation protocols with acceptable toxicity.

Watch out: Single-protocol series with no comparator arm, so survival cannot be attributed to the quad-shot schedule itself; the 'three cycles do better' finding is vulnerable to selection (dogs must live long enough, and stay well enough, to receive three cycles). The authors state toxicities were likely under-reported, and most dogs had advanced-stage disease (stages 3–4 in 77%), which shortens expected survival regardless of protocol.

Cabral I, Rigas K, Mason S, Benoit J, Elliott J. A Retrospective Evaluation of a Cyclical, Hypofractionated Radiotherapy Protocol ('Quad-Shot') for the Treatment of Canine Nasal Tumours in 81 Dogs. Veterinary and Comparative Oncology. 2025;23(4):606-615. PMID: 40851414. Registry ID: none in the record. MeSH: Animals · Carcinoma/radiotherapy · Carcinoma/veterinary · Dog Diseases/mortality · Dog Diseases/radiotherapy · Dogs · Dose Fractionation, Radiation · Female · Male · Nose Neoplasms/radiotherapy · Nose Neoplasms/veterinary · Radiation Dose Hypofractionation · Retrospective Studies · Treatment Outcome

Synthesis: curative-intent fractionated protocols are associated with roughly double the survival of palliative schedules in retrospective data, but intent is confounded and no randomised comparison exists

Synthesis

Who: Synthesis of the cards above: Sones 2013 (86 dogs with intranasal sarcoma, three-protocol retrospective comparison), Hayes 2025 (41 dogs with nasal carcinoma, two palliative schedules), Adams 2005 (53 dogs with malignant intranasal neoplasia, definitive 10 × 4.2 Gy protocol benchmark) and Cabral 2025 (81 dogs with sinonasal tumours, hypofractionated quad-shot series).

Result: (1) The only direct three-way comparison associates daily-fractionated/curative-intent treatment with the longest survival (641 days) and palliative protocols with the shortest (305 days) in sarcomas (Sones). (2) A definitive 10 × 4.2 Gy course alone produced a 19.7-month median survival and 44% 2-year survival across malignant intranasal neoplasia (Adams). (3) Within palliative treatment of carcinoma, more fractions did not buy more survival (Hayes), and a modern hypofractionated quad-shot protocol achieved a 296-day median survival with mostly mild acute toxicity (Cabral). The direction favours definitive intent where the dog and owner can sustain it; the size of the causal benefit is unknown because intent tracks stage and selection.

Watch out: Every carded record is retrospective; histologies differ between series (sarcoma in Sones, carcinoma-predominant elsewhere), staging and eras differ, and toxicity is not reported on a common scale. Cross-series survival comparisons should be read as ranges of experience, not as a league table of protocols.

Synthesis of Sones E et al. PMID: 23278974; Hayes A et al. PMID: 41047698; Adams WM et al. PMID: 16190593; Cabral I et al. PMID: 40851414. Registry IDs as on the individual cards.

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