by Lyndsay Kubicek, DVM DACVR (Radiation Oncology)
Angell Animal Medical Center
The most common type of genitourinary tract tumors in dogs is invasive transitional cell carcinoma1-4. Other carcinomas include squamous cell carcinoma, adenocarcinomas, and undifferentiated carcinomas. This group of tumors is locally invasive with a moderate-high metastatic potential to regional lymph nodes and distant sites. Mortality associated with these tumors is often attributed to urethral and/or ureteral obstruction. Survival time for patients without treatment is typically 1-2 months5.
Treatment intent ranges from palliation of signs to aggressive curative intent therapies. The infiltrative nature of genitourinary tumors renders complete surgical excision extremely difficult with the majority of tumors recurring 3-10 months following aggressive surgical resection6-9. Other treatments include the use of nonsteroidal anti-inflammatories (NSAIDS) with median survivals of approximately 6 months with this treatment alone 10,11. The use of an NSAID can be combined with high dose chemotherapy to increase survival times to 4.3-11 months12-15.
Radiation therapy has been previously evaluated for genitourinary tract tumors in dogs. Intraoperative radiation therapy has been used post surgically for microscopic disease resulting in survival times of 4-15 months16-19. Even with the potential for benefit, the use of such protocols was associated with severe late term radiation side effects. The inability to protect the normal structures and prevent severe late side effects was due to the limitations of the planning and delivery systems.
With the advent of newer planning and delivery techniques such as intensity-modulated radiation therapy (IMRT), we now have the ability to protect the adjacent critical structures. A new study by Nolan et al. demonstrated that image-guided intensity modulated radiation therapy was well tolerated with mild side effects. The subjective response rate was 60% and the median event-free survival time in this study was 317 days (10.4 months) and the median overall survival time was 654 days (21.6 months). This outcome appears superior to medical therapy (NSAID and or chemotherapy) with or without surgery 5, 10-19. A quality of life questionnaire was also used in this study and showed very favorable responses in regards to the owners’ perceptions of how their pets felt during and after radiation therapy. The patients in this study had various treatments before, during and after radiation therapy, however we can see that the addition of radiation therapy improved survival times with minimal impact on quality of life20.
Based on the information provided by the previously mentioned study, the addition of radiation therapy offers an exciting new tool in the treatment of genitourinary tract tumors in dogs. This treatment is available at Angell Animal Medical Center. If you would like further information please call the oncology service at 617-541-5136.
- Musters AJ, Widmer WR, Knapp DW: Canine transitional cell carcinoma, J Vet Intern Med 2003; 17:136-144.
- Knapp DW, Glickman NW, DeNicola DB, et al: Naturally-occurring canine transitional cell carcinoma of the urinary bladder: a relevant model of human invasive bladder cancer, Urol Oncol 2000; 5:47-59.
- Knapp DW: Animal models: naturally occurring canine urinary bladder cancer. In Lerner SP, Schoenberg MP, Sternberg CN, editors: Textbook of bladder cancer, Oxon, United Kingdom, 2006 Taylor and Francis.
- Gelberg HB: Urinary bladder mass in a dog, Vet Pathol 2010; 47:181-184.
- Sorennmo KU, Goldschmidt MH, Shofer FS, et al. Evaluation of cyclooxygenase-1 and cyclooxygenase-2 expression and the effect of cyclooxygenase inhibitors in canine prostatic carcinoma. Vet Comp Oncol 2004;2:13–23.
- Liptak JM, Brutscher SP, Monnet E, et al. Transurethral resection in the management of urethral and prostatic neoplasia in 6 dogs. Vet Surg 2004;33:505–516.
- Stone EA, George TF, Gilson SD, et al. Partial cystectomy for bladder neoplasia: Surgical technique and outcome of 11 dogs. J Small Anim Pract 1996;37:480–485.
- Norris AM, Laing EJ, Valli VE, et al. Canine bladder and urethral tumors: A retrospective study of 115 cases (1980–1985). J Vet Intern Med 1992;6:145–153.
- Helfand SC, Hamilton TA, Hungerford LL, et al. Comparison of three treatments for transitional cell carcinoma of the bladder in dogs. J Am Anim Hosp Assoc 1994;30:270–275.
- Knapp DW, Richardson RC, Chan TCK, et al. Piroxicam therapy in 34 dogs with transitional cell carcinoma of the urinary bladder. J Vet Intern Med 1994;8:273–278.
- McMillan SK, Boria P, Moore GE, et al. Antitumor effects of deracoxib treatment in 26 dogs with transitional cell carcinoma of the bladder. J Am Vet Med Assoc 2011;239:1084–1089.
- Henry CJ, McCaw DL, Turnquist SE, et al. Clinical evaluation of mitoxantrone and piroxicam in a canine model of human invasive bladder cancer. Clin Cancer Res 2003;9:906–911.
- Marconato L, Zini E, Lidner D, et al. Toxic effects and antitumor response of gemcitabine in combination with piroxicam treatment in dogs with transitional cell carcinoma of the urinary bladder. J Am Vet Med Assoc 2011;238:1004–1010.
- Arnold EJ, Childress MO, Fourez LM, et al. Clinical trial of vinblastine in dogs with transitional cell carcinoma of the urinary bladder. J Vet Intern Med 2011;25:1385–1390.
- Moore AS, Cardona A, Shapiro W, Madewell BR. Cisplatin (cisdiamminedichloroplatinum) for treatment of transitional cell carcinoma of the urinary bladder or urethra: A retrospective study of 15 dogs. J Vet Intern Med 1990;4:148–152.
- Turrel JM. Intraoperative radiotherapy of carcinoma of the prostate gland in ten dogs. J Am Vet Med Assoc 1987;190:48–52.
- Walker M, Breider M. Intraoperative radiotherapy of canine bladder cancer. Vet Radiol 1987;28:200–204.
- Withrow SJ, Gillette EL, Hoopes PJ, et al. Intraoperative irradiation of 16 spontaneously occurring canine neoplasms. Vet Surg 1989;18:7–11.
- Poirier VJ, Forrest LJ, Adams WM, et al. Piroxicam, mitoxantrone and coarse fraction radiotherapy for the treatment of transitional cell carcinoma of the bladder in 10 dogs: A pilot study. J Am Anim Hosp Assoc 2004;40:131–136.
- Nolan MW, Kogan LR, Griffin JT et al. Intensity modulated and image-guided radiation therapy for treatment of genitourinary carcinomas in dogs. J Vet Intern Med 2012; 26:987-995.