M3: Dr B, this is a 69-year-old Vietnamese man who came in for a cough. I thought it was just going to be a cold, but his wife noted that he has lost 20 pounds during the last 4 months without trying. I’m worried that he might have lung cancer.
Dr B: Lung cancer! Why are you thinking that?
M3: I didn’t really know where to start, so I started—anatomically—with the digestive system. He denied any trouble with his teeth, swallowing, abdominal pain, bloating, jaundice, diarrhea, or change in stools.
Dr B: Good. Then what did you do after that came up negative?
MS 3: I thought about the times in my life when I lost weight and how those might apply to him.
Dr B: Using your life experiences to relate to a patient? Good.
MS 3: Just seemed like common sense. So, during college I used to lose weight when I was really stressed out. And when I had mono, I lost 15 pounds. My junior year I was totally broke and had to live on ramen noodles for a month.
Dr B: So you used those experiences to ask him about . . .
MS 3: Depression or anxiety: negative. Symptoms of infections: except for the cough, nothing. Access to food seems OK; his daughter cooks for him, and there’s plenty. He doesn’t drink alcohol or use drugs. I also thought about when I re-started running, and I lost 10 pounds, but he hasn’t changed his activity.
Dr B: Excellent. How did you ask about depression?
MS 3: I read that, to diagnose depression, you need at least one of the two main criteria of feeling sad or not doing things you usually enjoy, so I asked him about those two things.
Dr B: One widely used screening test for depression, the PHQ-2, asks about those two things. Since the test is 95% sensitive, a negative result can help rule out depression. You mentioned weight loss when you had mono; think he might have that?
MS 3: Mono is pretty unlikely in a 69 year old, but infections like hepatitis or TB could cause weight loss. Hep B and TB are more common in Southeast Asians, but he has tested negative for both in the recent past.
Dr B: In addition to thinking anatomically or remembering personal experience, you might also think mechanistically. When someone is low on something, be it pounds or potassium, it means there’s not enough coming in or being made; too much going out or being used up; or it’s going to the wrong place. Our patient seems to be getting enough calories in, not losing a lot of calories externally, not doing more activity, so we’re getting down to...
MS 3: Something is making him burn more calories. That’s why I thought of cancer.
Dr B: How does cancer make someone lose weight?
MS 3: I’m not sure, but I have this picture of an evil cancer growing inside of him, and stealing all his calories, like a thief.
Dr B: Quite an imagination you have. Well, you are partly right. Malignant neoplasms tend to be more metabolically active than other tissues. That’s really the basis for chemo and radiation therapy: cells that are replicating faster will be destroyed first.
In addition, many cancers also produce hormones, such as Tumor Necrosis Factor, that inhibit appetite. Where might he have a cancer?
MS 3: The only complaint that he has is the cough, and he used to be a big smoker, so he could have a lung cancer.
Dr B: Very possible; lung cancer is the fourth most common cancer in US males, after skin, prostate, and colon. And, because of its higher mortality, it’s the leading cause of cancer death. Let’s summarize what we learned here today.
MS 3: (1) Two ways to think about undifferentiated complaints like cough are anatomically and mechanistically. (2) An effective way to screen for depression in primary care is with a two-question screen asking about depressed mood or anhedonia. (3) A good history can usually take you to a correct diagnosis. (4) Cancers can cause weight loss through hormonal appetite suppression or increased metabolism. (5) Lung cancer is the leading cause of cancer death in the United States.
Dr B: Superb! Now let’s go see him and talk with him about next steps.
John Brill, MD, MPH, University of Wisconsin, Author
Alec Chessman, MD, Medical University of South Carolina, Editor
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