Hi @laurapts there was a bit of chat about Prostap side effects on this thread Prostap - 1st injection - Going through breast cancer treatment / Hormone therapy - Breast Cancer Now forum. We have some more information on the website about side effects: Leuprorelin (Prostap) | Breast Cancer Now. However, neither of these mention a lump at the injection site.
Have you been in touch with our specialist nurses before? You may want to chat this through with them. You can get in touch with them here on the forum on the Ask our Nurses your questions board or on our helpline 0808 800 6000 which is open Monday to Friday 9am-4pm and 9am-1pm Saturday.
Sending our warmest,
Lucy