A book, movie, television documentary, etc. which exploits the sadness and drama of cancer. Such a work will often make the cancer patient (and/or caregiver) into a glowing hero/ine with boundless enthusiasm, energy, love and forgiveness. Cancer porn makes cancer look glamorous while down playing the pain and ugliness of the disease.
She: I hear that new movie "A Cancer Love Story" is really lovely! Sounds like a great date movie.
He: I hear it's maudlin CANCER PORN and should be avoided like a severe case of melanoma.