Shannen Doherty is set to undergo surgery yet again, a year after announcing her cancer was in remission.

The 47-year-old actress did not share the exact nature of the procedure but told fans on social media that per her doctor's recommendation it was suggested she use autologous blood banking - which means storing your own blood - ahead of the procedure.

The Charmed star captioned the photo: "My doctor had me bank some blood for my upcoming surgery. Mars P was patient with me and didn't even roll his eyes at my anxiety over the needle size. He was patient, kind and really good. (sic)"

She added: "As I sat there banking blood for myself, I asked him about some of the people also donating... especially the ones with TVs. So two of them come every 2 weeks and donate platelets which takes 2 hours. Another girl comes as often as allowed to donate blood.

"To say I'm moved by the generosity of people is an understatement. I'm vowing that as long as I'm cleared in the future, I will start donating.

"Thank you to those selfless humans that donate. Thank you to Mars and all at the clinic in Woodland Hills for your smiles and hard work. Thank you to the @americanredcross #humbledagain."

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Doherty was given the remission news on her cancer in April last year after undergoing eight rounds of chemotherapy and radiation treatments, as well as a single mastectomy.