Psychiatric nursing care plan.

I am a student working on a care plans for a psychiatric patient who has schizophrenia. She was also recently diagnosed with stage 2 lung cancer, but has no insight into this diagnosis. In writing a nursing diagnosis, I was thinking of ineffective coping, but I am unsure of the related to aspect. Could I say "ineffective coping r/t recent lung cancer diagnosis"? Or does the r/t have to pertain to her schizophrenia? All advice is appreciated?