Good evening,

Our oldest, Chief, recently had his front left leg amputated due to Apocrine Sweat Gland Adenocarcinoma initially found when we had his dewclaw removed due to a history of infection and complications back in April 2021.  The tumor was biopsied at the time and that is when we found out that our Chief had cancer.  We had our first oncology consult in Sandy Springs, GA in early-May.  They gave us three options, but based on the first pathology report recommended radiation or amputation versus wait and see.  After much research, consultation and deliberation we decided to amputate as the conservative approach given how much time left we expected he would have to live once the cancer was fully removed.

The amputation occurred in mid-August, and we just received the most recent pathology report.  It makes mention that there "may be potential for metastasis," but it also states there "is no evidence of lymphatic or vascular invasion."

Based on this report, the surgeon and DACVIM oncologist have both recommended Carboplatin Chemo.  His 5 chest X-Rays and abdominal ultrasound were both clear immediately prior to the amputation. His bloodwork was also clean.  Given this and that the "margins proximally are free of tumor", does Chemo seem necessary?  The initial oncologist stated that this type of cancer had a very low metastasis likelihood.  Does the higher MI index truly correlate to a metastasis rate or only the higher certainty to regrow or spread locally like the journal publications state?  We do not want to subject him to Chemo if not absolutely necessary as the amputation has already been more traumatic to him versus what was originally stated.  

Thank you so much in advance for your help in this trying time.  

Chief is a 13 year old Chihuahua-Terrier mix, with a slight heart murmur, but otherwise a clean medical history.  The full pathology report has been re-typed below:

Microscopic Description: Sections from the amputated leg after decalcification consist of haired skin with a tumor mass. The tumor consists of multiple epithelial structures forming clusters, glands and tubular like structures. The cells are cuboidal to tall columnar with abundant amount of slightly vacuolated cytoplasm. Clusters and clumps of tumor cells are separated from one another by abundant amount of fibrous stroma. Nuclei are moderately pleomorphic, round to oval and have prominent nucleoli. A few large nuclear forms are present. Mitoses are 1-3 per high-power filed and are 25 per 10 fields. The tumor is very invasive into surrounding tissue and invades into bone but there is no evidence of vascular or lymphatic invasion. Margins proximally are free of tumor.

Microscopic Findings: Poorly differentiated apocrine sweat gland adenocarcinoma

Comments: This is a poorly differentiated tumor that is very invasive and invades into bone but is completely removed at the leg is amputated. There is no evidence of lymphatic or vascular invasion. The chance of recurrence is low, but there may be potential for metastasis.