How serious if my friends diagnosis of invasive carcinoma ductal with medullary carcinoma?

Not trivial! Breast cancer, is most commonly of the invasive ductal type. Often there are mixed patterns with medullary or lobular histologies. Perhaps others as well. The most important factors however aren't mentioned here. Age, stage, grade, lymph node involvement all play a much more prognostic role at this point.

Related Questions

My friend has invasive carcinoma medullary carcinoma. Whats that mean?

Need more info. Medullary carcinoma is not organ specific and is a discription of how cancer looks like under microscope. Medullary cancer can be described in breast cancer, thyroid cancer for example. Thus the prognosis and treatment really depends on the origin of the cancer.