With very limited information provided by you it is very difficult to comment on this issue. What form of lymphoma
is he suffering form? hodgkin's or non-hodgkin's? if non hodgkin's lymphoma then exact sub-type to be mentioned. however in most of the lymphoma chemotherapy
is incorporated which is a cardiotoxic drug. I do not understand the meaning of heart pain. It may be due to angina or may be due to lymphoma itself or from other pathology. Anyway if your father has been suffering from heart problem then based on baseline echocardiography
doxorubicin may be omitted from chemotherapy regime. Consult your oncologist
and cardiologist. Take care of your father.