Patient:
‘Bo’ – 7yr old entire male Golden Retriever.
History:
Progressive weight loss (6kg) over previous four weeks. Initially appetite remained good, but had dopped right off and now will only eat smackos. Vomiting only intermittently initially, but every 2 days in recent week. Tarry black faeces noted. Increased drinking in last week only.
Demeanour is only mildly reduced.
Clinical Assessment:
Routine blood testing at regular vet showed hypercalcaemia (3.5mmol/L total calcium), mild low albumin 22g/L and inflammatory leucogram as only changes.
Hypercalcaemia of malignancy was highly suspected with degree of weight loss and normal biochemistry. Vomiting and black stool made the GIT a likely origin organ.
Lymphosarcoma and Anal gland adenocarcinoma are the two most common tumours responsible for hypercalcaemia (although any tumour can potentially produce PTHrp).
Rectal examination revealed no abnormality palpable in anal glands.
Ionised Calcium confirmed functional hypercalaemia – 2.0mmol/L (1.2-1.4)
This degree of hypercalcaemia is acutely threatening to renal function and immediate IV fluid diuresis was instituted – 0.9% NaCl.
Abdominal ultrasound and chest radiography was performed to image the body cavities.
Chest radiographs were unremarkable.
Abdominal ultrasound showed multiple abnormalities:
- Bilateral renomegaly with heterogenous echotexture.
- Mildly coarse splenic parenchyma and mild splenomegaly.
- Markedly thickened gastric wall with loss of normal layering and compliance.
- Cranial abdominal lymphadenopathy.
- Lymphosarcoma was highly suspected by this stage.
Ultrasound guided fine needle aspirates were obtained from the Kidneys, Spleen and Gastric wall, under sedation, for cytology assessment. Cytology confirmed a high grade lymphosarcoma in the kidneys and stomach with suspicion of splenic involvement.
Immuno-cytochemistry was requested on the submitted cytology slides to differentiate between B & T cell lymphosarcoma. Immuno-cytochemistry is a relatively new availability and can mean that a biopsy and histopathology is not always required prior to commencing chemotherapy. Immunocytochemistry showed a B cell lymphosarcoma.
The major favourable prognostic indicators for Lymphosarcoma Chemotherapy treatment are that the patient is well (Sub-stage A), the tumour is a B cell variant, and initial positive response to chemotherapy. Other factors that have been linked with a negative prognosis are visceral organ involvement (GIT, renal, hepatic), hypercalcaemia, and T cell variant.
So Bo has several negative indicators present – He is clinically unwell, he has visceral involvement and he has moderately severe hypercalcaemia.
The expected survival times over a population of dogs with high grade lymphosarcoma without treatment is 4-8 weeks.
With a CHOP based chemotherapy protocol (Maddison-wisconsin) the expectation from population data is of an 80% survival rate at 12 months and 50% survival at 18 months.
It is important to remember that population data is a guide but individual responses can be very varied. Prognostic indicators are important but should not be viewed as infallible. Response to chemotherapy remains the most important factor and unfortunately is a hindsight analysis.
Bo’s owners were very dedicated and elected to commence chemotherapy after a thorough discussion of the above factors, the expected ‘good’ outcomes, the potential for negative side effects and survival times.
Cortisone use with chemotherapy has been recently shown to reduce survival times/tumour responses in cases that are clinically well (sub-stage A). However, the positive effects of appetite stimulation and anti-inflammatory effects are beneficial in the unwell patient.
Without chemotherapy, prednisolone palliation alone can have a dramatic effect on reducing lymphadenopathy and keep the patient feeling well. The theory is that this treatment does not extend survival time, but again individual cases have shown many months of survival with prednisolone as a sole medication. The variability in individual responses explains the need for strongly designed studies with large numbers of patients to get scientifically significant information on treatment responses.
Bo was started on vincristine, prednisolone and continued 0.9% saline diuresis. 24hrs later his hypercalcaemia had resolved, he was eating very well, and he was discharged home.
The Maddison-Wisconsin protocol consists of 4 repeated cycles of 4 chemotherapy treatments – Vincristine, Cyclophosphamide, Vincristine and Doxorubicin respectively.
Bo received his final chemotherapy treatment in mid-January 2017 after approximately 6 months of treatment. A complete re-staging was performed after the first 4 treatments which showed no grossly visible cancer.
He required one 36hr hospitalisation due to a severe neutropaenia and pyrexia after the first cyclophosphamide treatment. This responded well to IV fluids and anti-biotic administration. Bo did not have any other negative events during his chemotherapy course.
Bo is now in his medication free stage of treatment. Cure is very unlikely but the hope is for many months of disease free time.
Chemotherapy in pets is aimed at increasing the quality and quantity of life. Managing owner expectations is important, as is dispelling/alleviating the deep fear that the word ‘chemotherapy’ induces in a lot of people.
The addition of half-body radiation into the chemotherapy protocol is currently under assessment at BVSC and has the potential to further increase survival times, and hopefully, the number of cures possible. The radiation component of the treatment replaces the 2nd cycle of the Maddison-Wisconsin protocol and can be performed as an outpatient procedure with the remainder of the treatments conducted locally.
At NCVS, we have a Class-III chemotherapy cabinet which enables in-house dispensing of chemotherapy agents and dose adjustments as required for changing patient/tumour responses.
If you have any queries with regard to chemotherapy or any other oncology enquiry, please feel free to call the clinic.
