Hello @shing and welcome to Mayo Connect. Hairy Cell Leukemia is a rather rare form a blood cancer affecting the white blood cells. It’s generally a very slowly developing disease so your father may not require any treatment for a while. It will depend on the diagnoses and stage of his disease. If this was newly discovered hopefully he’s in the early stages and won’t require anything more than watchful waiting.

Here are a few articles that give you an overview of the disease.
https://www.mayoclinic.org/diseases-conditions/hairy-cell-leukemia/symptoms-causes/syc-20372956
https://www.cancer.org/cancer/chronic-lymphocytic-leukemia/treating/hairy-cell-leukemia.html
There aren’t many conversations in our forum with HCL but I did find this discussion with a few members. It is older but you can reverse the order of the the conversations by clicking the link under the subject where it says “oldest to newest”. Click there and the latest replies will be first.

Hairy Cell Leukemia
https://connect.mayoclinic.org/discussion/hairy-cell-leukemia/
To help bring other members into the discussion, are there any specific questions you have?

@shing, I'd like to add my welcome. I have moved your message to the existing discussion that @loribmt suggested here:
- Hairy Cell Leukemia
https://connect.mayoclinic.org/discussion/hairy-cell-leukemia/

Hi, I follow the hematology area of Connect and hairy cell leukemia jumped out at me in the updates tonight. My husband was diagnosed a long time ago with HCL when there was no treatment beyond removal of the spleen. Problem was his blood counts were so critically low he could not have survived surgery and was in fact told he would not live through the week.

Miraculously, we found a clinical trial available at a cancer center in our city for alpha interferon. He took daily injections for 5 or 6 years achieving partial remission status. FDA approved it for HCL use sometime during that period. We learned through trial and error that he could manage the accompanying flu like symptoms by injecting himself right after dinner and sleeping through any ill effects. He awakened feeling well except when infections would arise which we sought treatment for immediately.

When his peripheral blood counts declined and the hairy cells once again replaced most healthy cells in the bone marrow, he opted to try another experimental treatment we found out at Scripps Institute in LaJolla , CA. As I recall, he was patient #125 in the world to receive 2-cda. It took some time for the bone marrow to recover, but the 5 days of in-clinic infusions put him in complete remission for the first time since diagnosis! He did have a bleed due to picking up a heavy book in the arm he received his infusion and other side effects during treatment which was scary as we were staying in an RV off site, but well worth the bonus years it gave him we would not have otherwise had. I recall the complete remission was fairly short lived (maybe a year or so) before it returned to a partial
remission. Even the latter was a great gift.

Both treatments provided a good quality of life for him after we made some adjustments and grew less fearful of what comes next. We made a lot of memories and managed to have a lot of fun despite challenges along the way.

Those included the infections I mentioned which all resolved with antibiotics and antivirals plus other malignancies. At Scripps, as they examined him before starting the 2-cda, they found an enlarged lymph node which they surgically removed and biopsied before they would go forward with the treatment. It was non Hodgkin's lymphoma which those doctors said was related to the Hairy Cell leukemia. I can't be certain, but it's possible the Drs there said both the HCL and lymphoma involved B cells. The 2-cda handled both. Beyond that, he
had a large number of squamous cell carcinomas due to his being immunocompromised.

14 years post diagnosis, his numbers had deteriorated to a critical level and he
chose to try a 3rd experimental drug with documented mortalities. Not surprisingly, he, too, didn't make it. But what I would say to you about anyone with cancer is that it's possible for a patient to continue having a satisfying life, sometimes more so after diagnosis. There are many variables, but he had an amazing attitude and was determined not to let cancer be the focal point of his life. And he didn't have to, lol, because he had someone charting counts looking for trends, being hypervigilant about catching infections early, making sure they were treated aggressively, etc. And that worked for us because I would have been crazy if I had felt there was nothing I could do to help. Most people couldn't believe he had anything wrong as he never lost his hair, had a port, but most always had a smile on his face and a twinkle in his eye. That served me well when my time came a couple of years ago. When diagnosed with first breast then colon cancer, I thought, "hey, I got this because I know exactly what to do." I had started volunteer counseling cancer patients soon after he was diagnosed and he'd been my cancer role model . I'm no Dr or medical professional, but things I suggest based on data and personal experience: Call the National Cancer Institute (800-4-Cancer) with a diagnosis and ask for the name/contact info/location of a Comprehensive Cancer Center you can get to. When there, have them confirm the diagnosis and formulate a treatment plan which may be able to be done back home with their oversight. You want best advice as to that first treatment option because if it doesn't work, it may preclude your ability to have a treatment in trial that would. In example, had my husband had a splenectomy, he would have been ineligible for the
alpha interferon trial. I ran as fast as I could to Mayo Clinic JAX for
those reasons for pre-myeloma and my 2 cancers. So far so good - I'm cancer free 🙂 I went on longer here than I should have but saw so little on HCL here, I wanted to share 14 years worth of experience with you. Blessings to all...