January 01, 2019

An X-ray shows a spot on my lung. Is it likely cancer?

Q: A spot was seen in my lung on a chest X-ray taken for another reason. My doctor said it's unlikely to be cancer, but scheduled a follow-up CT scan just in case. How does my doctor know it's probably not cancer?

A: A single white spot on a lung (solitary lung nodule) is a common finding on chest imaging done for another reason. Although most nodules are noncancerous, it can be worth examining the finding for cancer. If detected early, lung cancer is typically treatable and even curable with surgery.

Most of the time, lung nodules are scars or markings from a previous inflammation or infection. A noncancerous tumor (hamartoma) also can occur. Estimating your risk of a cancerous tumor can be done fairly reliably by considering some factors, including:

  • Nodule size and appearance — The risk of a nodule being cancerous increases with size. Nodules that are less than 6 millimeters are the least likely to be cancerous. Solid, smooth-edged nodules are less likely than nodules with irregular edges to be cancerous.
  • Age and health history — Being older increases the risk of a nodule being cancerous, as does having had a prior cancer in the chest and being a current or past smoker.
  • Pace of changes over time — Growing and changing nodules are more concerning than stable ones. Growth or other changes can be determined by comparing your current imaging test with a past imaging test, if available.

Using clinical experience and possibly a risk calculator, your doctor can determine the odds of a nodule being cancerous. Very low-risk nodules may require limited follow-up imaging. Higher risk nodules will likely have additional follow-up with added imaging or possibly...