Page 1281 - Cote clinical veterinary advisor dogs and cats 4th

Melanoma 645

• Chemotherapy for all patients treated defini- Recommended Monitoring • Prognostic factors
tively with surgery and/or radiotherapy due Initially, patients should be monitored with ○ Mitotic index is the most important
VetBooks.ir ○ Systemic therapy with carboplatin or radiographs (to identify metastatic disease) every ○ Breed: Doberman pinschers and Diseases and Disorders
prognostic factor: ≥ 3 mitoses/HPF
to high rate of metastatic disease
physical exam (local disease status) and thoracic
indicates malignancy.
cisplatin given reported activity of
2-3 months. Frequency is altered by individual
carboplatin in dogs with melanoma
○ Chemotherapy may benefit patients treated factors. miniature schnauzers more likely have
benign melanoma (75%); miniature
with palliative radiotherapy and those with PROGNOSIS & OUTCOME poodles more likely have malignant
evidence of distant metastasis. melanoma (85%).
• DNA-based melanoma vaccine (Oncept, Oral melanoma:
Merial) is indicated for all patients for which • Prognosis PEARLS & CONSIDERATIONS
local/regional control has been attained. ○ Untreated: median survival of 65 days
Subungual (nail bed) melanoma: ○ Conservative surgery alone: median Comments
• Radical excision of mass if survival of 3-4 months; local recurrence • Radiation treatment
○ Wide surgical margins (>2 cm, including rate > 70% ○ Melanoma has a greater capacity for
underlying bone) are possible, and ○ Radical surgery alone: median survival of sublethal damage repair and therefore
○ Patient has no distant metastatic disease 19 months for stage I (<2 cm), 4 months is best treated with a hypofractionated
• Limb amputation (plus excision of associ- for stage II (2-4 cm without lymph node (larger doses per fraction) treatment
ated lymph nodes if metastasis) should be metastasis) and stage III (>4 cm or lymph protocol, such as 8-9 Gy/fraction 3-4
considered if wide surgical margins cannot node metastasis present); local recurrence times instead of conventional protocols
be obtained with local resection (i.e., digital rate of 22% after mandibulectomy and (e.g., 3-Gy/fraction 16-19 times).
amputation). 48% after maxillectomy ○ For treatment of malignant melanoma, a
• Removal of macroscopic tumor followed ○ Radical surgery with or without hypofractionated protocol is used in most
by definitive course of radiation therapy adjunctive treatment: median survival facilities, and a conventional radiation
to primary tumor site and regional lymph of 21-29 months for stage I, 8-27 protocol is not used currently.
nodes if months for stage II, and 6-7 months for ○ Four reported veterinary protocols for
○ Digital amputation not possible, and stage III melanoma are 10 Gy × 3, 9 Gy × 4, 8
○ Regional lymph node metastasis is identi- ○ Radiation therapy for microscopic tumors: Gy × 3, and 4 Gy × 12.
fied, and median survival of 15 months; local recur- ○ Because late-responding normal tissues
○ Patient has no distant metastatic disease rence rate of 26% (bone, muscle, central nervous system)
• Palliative course of radiotherapy could be ○ Radiation therapy for macroscopic tumors: are more susceptible to toxicosis with
considered if response rate of 82%-94%; median sur- larger doses of radiation, large doses
○ Patient has distant metastatic disease and vival of 5-12 months; local progression/ (8-10 Gy) should be avoided in patients
clinical signs associated with local disease recurrence rate of 45% for which long-term survival (>12 months)
result in decreased quality of life ○ Chemotherapy for macroscopic tumors: is expected.
• DNA-based vaccine and possibly chemo- response rate of 18%-37%. • Chemotherapy
therapy should be considered for all patients ○ Chemotherapy for microscopic tumors: ○ In patients failing platinum-based chemo-
treated definitively with surgery and/or progression-free interval of 9 months therapy, veterinary and human informa-
radiation therapy due to the high rate of with adjuvant carboplatin after surgical tion may support the use of dacarbazine,
metastatic disease in patients with subungual resection or surgical resection combined melphalan, CCNU, piroxicam, and
melanoma. with radiation therapy interferon.
Cutaneous melanoma: ○ Prognosis for definitively treated feline • DNA-based vaccine
• Surgical resection is the treatment of choice oral melanoma is not known. ○ Studies indicate that patients with locally/
for benign melanomas (<3 mitoses/10 HPF). • Prognostic factors regionally controlled disease may experi-
• Radical excision of malignant cutaneous ○ Stage ence a longer survival when the tyrosinase
melanoma (≥3 mitoses/10 HPF) if ○ Mitotic index ≥ 4 mitoses/HPF has been DNA vaccine is administered.
○ Wide surgical margins (>2 cm) can be associated with an increased risk of death ○ The utility of tyrosinase DNA vaccina-
obtained, and within 1 year of diagnosis (90% sensitivity tion in patients with advanced disease is
○ Patient has no regional lymph node or and 84% specificity). unclear.
distant metastatic disease Subungual melanoma:
• Removal of macroscopic tumor followed • Prognosis Technician Tips
by definitive course of radiation therapy to ○ Surgical excision (local or limb amputa- Do a complete oral exam during professional
primary tumor site and regional lymph nodes tion): median survival of 12 months; local dental cleanings, and bring all identified oral
if recurrence rate of 30% (local resection masses, even very small masses, to the attention
○ Radical excision is not possible or if only) of the clinician for possible biopsy under the
regional lymph node metastasis is identi- ○ Role of radiation therapy and chemo- same episode of general anesthesia.
fied, and therapy undetermined
○ Patient has no distant metastatic disease ○ Prognostic factors: none identified SUGGESTED READING
• Palliative course of radiation therapy could Cutaneous melanoma: Bergman PJ, et al: Melanoma. In Withrow SJ, et al,
be considered if • Prognosis editors: Small animal clinical oncology, ed 5, St.
○ Patient has distant metastatic disease and ○ Surgical excision: median survival of Louis, 2013, Elsevier, pp 321-334.
clinical signs associated with local disease 24 months (benign); 7-11 months AUTHOR: Tetsuya Kobayashi, DVM, MSpVM,
result in decreased quality of life (malignant) DACVIM, DAiCVIM
• DNA-based vaccine and possibly chemo- ○ Efficacy of radiation therapy and chemo- EDITOR: Kenneth M. Rassnick, DVM, DACVIM
therapy should be considered for all patients therapy undetermined
with malignant cutaneous melanomas treated ○ Median survival for feline cutaneous
definitively with surgery and/or radiation melanoma treated with surgery alone is
therapy. 12 months.

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