In May 2024, when Jimmy’s left shoulder developed an egg size lump-which was later removed and found to be not cancerous-the CT at the time showed he had a small lump in his right lung that looked like a small “curved vessel”. By March 2025, it was a small marble size nodule. He then had surgery April 2025 to remove it. Test results came back positive for cancer.
But he had clean margins-meaning they removed the part of the lung lobe that had the cancer. Chemo was not necessary but I was afraid that if we were not aggressive when we could be while he was medically stable with his heart and kidneys, that the cancer could spread or return.
So, in May, for once a month for four months, ending in August 2025, he had chemo. He had to be slightly NPO-he could eat a small amount in the morning but nothing past 10 a.m. He had chemo around 3 p.m. The process was less than 15 minutes but we were usually there for about 30 minutes as they wanted to make sure he tolerated it well. He never needed anesthesia although some cats do. In that case, he would have had to have been NPO-nothing to eat in the morning at all. I did have to make sure he was not vomiting once we were home and that he recovered well during the month. He never had vomiting or gastro issues like humans do and he ate well and moved around well. But he did become more exhausted as time went on but nothing that was concerning.
He was given ondansetron to take twice a day-a medication that helps with chemo treatment nausea. He continues to take the drug still. He was expected to take it for a few weeks after his last session which was late in August but when we tried to remove it in December, he ate less. While a cat may not seem to be sick from chemo, does not lose their hair or vomit from it, they can still be nauseous, and are physically worn out. Listed below is the March 2025 CT report and the April 2025 lung cancer test results.
His March 2025 CT scan report prior to surgery to remove the lung lobe and nodule:
“Mar 18, 2025
Thoracic CT, pre-contrast and postcontrast, transverse, dorsal and sagittal images:
Lungs: Within the 6th IC space ventrally, there is a well-circumscribed, mildly irregular nodule, approximately 1 x 1 x 1 cm, larger than on the previous study. This is suspected to be within the caudal aspect of the right middle lung lobe, previously thought to be within the right caudal lung lobe.This is near the pleural surface and adjacent to the cardiac silhouette. There is mild enhancement of the pulmonary nodule.
Heart and pulmonary vessels: Definitive cardiac abnormalities are not identified. Unremarkable pulmonary vessel size and shape. Mediastinum: No masses. Unremarkable trachea and esophagus.
Sternal lymph nodes are mildly enlarged with mild contrast-enhancement. Tracheobronchial lymphadenopathy is not identified. Pleural space: Significant abnormalities are not identified.
…
CONCLUSION:
Solitary right mid-pulmonary nodule, increased in size compared to the previous study, new sternal lymphadenopathy. This is suspected to be within the caudal aspect of the right middle lung lobe, less likely cranial aspect of the right caudal lung lobe. Metastatic neoplasia is the primary differential. A primary pulmonary tumor or granulomatous mass is not ruled out.
…
CONCLUSIONS:
Nodular hepatopathy. Rule out vacuolar hepatopathy, chronic hepatitis, less likely metastatic neoplasia. Subjective focal small intestinal thickening...
Discussion: Jimmy's CT scan revealed that he continues to have a single pulmonary nodule that has increased in size now measuring ~1cm. There are no other pulmonary nodules noted. Mild sternal lymphadenopathy is a non-specific finding. Although a single nodule of this size could be consistent with metastatic disease (unknown primary), I am more suspicious of a primary tumor. If this represented metastatic disease I would expected more nodules over the last several months. The most common primary lung tumor in the cat is called a bronchoalveolar carcinoma and arises from the cells that line the lung. The majority of bronchoalveolar carcinomas in the cat are high grade and tend to grow quickly and metastasize quickly. My suspicion therefore is that if Jimmy does have a primary lung carcinoma then it is more likely to be low grade given that it is growing relatively slowly (~1mm monthly). However, the reality is that we never know the answer to this question without removal of the mass and histopathology. This may represent a less common tumor or even a benign tumor (although this is considered less likely in the lung).
The treatment of choice for primary lung masses is surgical removal via lung lobectomy. I did have our surgery service evaluate the CT scan and they would approach this tumor laterally (approach between the ribs) versus having to perform a median sternotomy. If surgery is something that you are interested in then we can set up an in-house surgical consultation where the surgeon calls you at home to discuss the surgery. They can provide an estimate and can even schedule him if you would like.
Alternatively, if surgery is not desired then we could continue to monitor this mass with pulmonary radiographs to continue to assess its growth rate over time. This is a more palliative approach but not unreasonable especially in cats as they age.
…”
Lung Cancer Test Result:
“ Jimmy's histopathology results were consistent with a diagnosis of a pulmonary adenocarcinoma that has been removed with complete surgical margins. The removed lymph node only revealed evidence of reactivity (lymphoid hyperplasia) and multifocal lipogranulomas; no evidence of any lymph node metastasis which is great news. There is no consistent grading system for pulmonary adenocarcinoma in cats however based on the mitotic rate (9 per 10/hpf) and mild/moderate atypia I would consider this tumor to be of low/intermediate grade.
Per our original conversation; there is not a lot of information on low/intermediate pulmonary adenocarcinoma in cats since most cats diagnosed with this cancer have rapid progression. The overall metastatic rate of this disease is thought to be >50% in cats and many cats have evidence of metastasis at the time of diagnosis.
In Jimmy's case; we watched this mass grow quite slowly over a several month period and there was no evidence of any movement therefore it is reasonable to believe that surgery may be curative or provide long term local control. At the same time, it would not be completely wrong to consider further intervention with chemotherapy since we are definitiely in a position of the unknown. I think both are reasonable directions.
If we decided to consider a monitoring schedule then our plan would be to perform a physical exam and recheck thoracic radiographs once every 3 months for 1 year and then twice yearly. This can be performed here or with your primary veterinarian (whichever is most convenient).
If further intervention is desired then I would recommend that we consider using a drug called carboplatin. Carboplatin is an IV chemotherapy agent that is given once every 4 weeks in cats for a total of 4 treatments. Carboplatin tends to be well tolerated in the cat with a side effect rate of ~10-15%. Possible side effects include: lethargy, inappetance, nausea, diarrhea and/or bone marrow suppression. Side effects usually occur 3-5 days following therapy, persist for 1-4 days and then resolve. Medications can be provided if needed and dose adjustments can also be made (most side effects are dose related). An estimated cost of carboplatin is ~$900 per treatment. Recheck thoracic radiographs are performed at the time of the 4th treatment to look for any evidence of metastasis in spite of therapy.
Overall, I am very happy with these results. We know that this mass was growing quite slowly and has been removed with complete surgical margins. We are just hampered by the lack of data in cats for this type of cancer therefore it is hard to predict the future in Jimmy's case. He may do absolutely fine without further intervention and he is an older cat with other co-morbidities. At the same time, I cannot be completely confident that metastasis will not form in the next 6-12 months. Please do not hesitate to call with any questions or concerns.”
We began carboplatin chemotherapy protocol May 2025 until August 2025. He had follow-up xrays in August.
“We are so proud of Jimmy! He looks amazing! His physical exam was unchanged and his recheck thoracic radiographs did not reveal any evidence of regrowth or spread of his pulmonary carcinoma which is great news! Jimmy's complete blood count from yesterday was ok for chemotherapy and Jimmy received his fourth and final carboplatin treatment in the hospital today as planned. At this time I recommend that we place Jimmy on a monitoring schedule consisting of a physical exam and recheck thoracic radiographs once every 3 months until we hit the year from surgery and then twice yearly after that. Please do not hesitate to call with any questions or concerns.”
There was one concern on the xray:
“ Aug 20, 2025
Three-view thorax, three images:
There are metallic clips near the hilus associated with lung lobectomy.
Discrete pulmonary nodules are not identified.
Within the right mid thorax, there is a poorly defined soft tissue opacity…
CONCLUSION:
Right sided lung lobectomy.
Pulmonary nodules are not identified.
Poorly defined right mid thoracic soft tissue opacity. Rule out atelectasis, fibrosis. Poorly defined neoplastic re-growth is not highly suspected. This can be re-evaluated at scheduled follow-up imaging with the oncology service. **This is most suspicious for fibrosis.”
We were concerned that this was a return of cancer or fibrosis. Fibrosis is when tissue in the lung is damaged-from disease, the environment, or cancer-and scar tissue builds up. If too much tissue builds up, the lungs cannot produce oxygen and the patient eventually suffers from not being able to breathe nor send oxygen to the rest of the body, heart, kidneys, muscles, etc.
However, his recent February 2026 checkup with oncology showed that the fibrosis is decreasing and healing so that it is likely post-surgical scaring that will hopefully improve but it is not yet worsening. When I spoke to his cardiologist about this in September 2025, she said that the lung-the rest of the lung and the other lung lobe-can compensate for fibrosis as long as there is enough of a lung remaining that is not scarred. And that she has seen cats with far worse fibrosis than Jimmy’s and do very well.
So, as of February 2026, we are breathing a sigh of relief for now regarding his lungs. He returns in May for another checkup with oncology at which time they will schedule another CT with contrast if he is able to have anesthesia. And he will have a cardiology checkup prior to that to determine if he can.
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