Abstract

A 0.5-kg female adult common squirrel monkey, Saimiri sciureus, of unknown age was evaluated for a 7-month history of a nonhealing lesion and discharge around both nares. Upon examination, a 10-mm diameter area of crusted proliferative tissue was noted over the nares. The left nostril was stenotic. Histopathologic examination of an incisional biopsy of the tissue was consistent with a basosquamous cell carcinoma. No evidence of metastatic lesions was found on physical examination or full-body radiographs. Computed tomography revealed a soft tissue mass arising on the rostrum. The mass extended 3 mm deep to the surface, and the underlying nasal cavity and bone were normal.

Treatment with oral piroxicam (Feldene®, Pfizer) at a dosage of 0.3 mg/kg was initiated. Piroxicam was given every other day for the first 7 days and then daily. To facilitate oral dosing, piroxicam was suspended in sterile saline to yield a concentration of 0.25 mg/ml.

Tumor size was measured at 2, 4, 8, and 12 weeks after beginning treatment. After 4 weeks of treatment with piroxicam, there was a 10% reduction in tumor area, overall thickness was reduced, and the tissue appeared less inflamed and drier. The monkey appeared significantly more comfortable, spent less time rubbing its face, and its social activity was increased. However, by week 8 tumor size progressed, and by week 12 the animal’s quality of life had deteriorated. The monkey was euthanatized. Necropsy findings did not reveal any lesions suggestive of treatment toxicity.

Piroxicam is a class I nonsteroidal anti-inflammatory drug (NSAID) originally approved to treat arthritis in humans.⁵ In addition to its anti-inflammatory effects, numerous experimental and clinical trials have proven piroxicam to be effective in treating carcinomas in animals and humans.^2-4 The mechanism of action that defines NSAIDs as a class is their ability to inhibit cyclooxygenase (COX), the enzyme that metabolizes arachidonic acid into prostaglandins. Two distinct isoforms, designated COX-1 and COX-2, have been recognized. COX-2 is the isoenzyme involved in the progression of some neoplasias. The proposed mechanisms of action against tumors include modulation of inflammation and immunosuppression, increased apoptosis, anti-angiogenesis and decreased tumor cell invasiveness.^1,6

Treatment in this case was considered successful in that there was qualitative improvement in appearance of the tumor and improved attitude and comfort of the monkey. A major benefit of piroxicam was the ability to treat the animal within its normal social setting. The monkey was easily medicated each day without disruption of its daily activities and without removal from the group. This is in contrast to other potential treatment options available to treat invasive neoplasms of the nasal planum, such as radiation therapy, which would have required removal for extended periods of time. As an important goal in this case was to maintain quality of life, the authors feel that the use of piroxicam, when compared to other treatment options, provided a better quality of life, even if for a shorter period of time.

Acknowledgments

The authors would like to thank the curatorial and keeper staff of the Rosamond Gifford Zoo at Burnet Park, Syracuse, NY, for their contributions and support; and Drs. Michael Garner, Ned Dykes, Sean McDonough, Noha Abou-Madi and Sonia Hernandez-Divers for their assistance with this case.

Literature Cited

1.  Khan, K.N., D.W. Knapp, D.B. DeNicola, and R.K. Harris. 2000. Expression of cyclooxygenase-2 in transitional cell carcinoma of the urinary bladder in dogs. Am. J. Vet. Res. 61: 478–481.

2.  Knapp, D.W., R.C. Richardson, T.C.K. Chan, G.D. Bottoms, W.R. Widmer, D.B. DeNicola, R. Teclaw, P.L. Bonney, and T. Kuczek. 1994. Piroxicam therapy in 34 dogs with transitional cell carcinoma of the urinary bladder. J. Vet. Intern. Med. 8: 273–278.

3.  Pollard, M., and P.H. Luckert. 1989. Prevention and treatment of primary intestinal tumors in rats by piroxicam. Cancer Res. 49: 6471–6473.

4.  Schmidt, B.R., N.W. Glickman, D.B. DeNicola, A.E. de Gortari, and D.W. Knapp. 2001. Evaluation of piroxicam for the treatment of oral squamous cell carcinoma in dogs. J. Am. Vet. Med. Assoc. 218: 1783–1786.

5.  Taketo, M.M. 1998. Cyclooxygenase-2 inhibitors in tumorigenesis (part I). J. Natl. Cancer Inst. 90: 1529–1536.

6.  Thun, M.J., S.J. Henley, and C. Patrono. 2002. Nonsteroidal anti-inflammatory drugs as anticancer agents: mechanistic, pharmacologic, and clinical issues. J. Natl. Cancer Inst. 94: 252–266.