Hi, my father-in-law has been detected with 4th stage lung adenocarcinoma, june, 2017. He is having a history of tobacco chewing. Pet-ct and ct scan suggested that the cancer has spread to lymph nodes and some part of abdomen. He completed his 4 rounds of chemotherapy with carboplatin and pemetrexed and he is now on targeted therapy of erlotinib. He is responding well with that treatment, but he had fissure like symptoms from last 3 days, like bleeding from stool, but today he is fine. What can be the cause of this symptom? Is it related to cancer?