Episode 023: Lung Cancer Series, Pt. 1: Approach to concerning lung nodules

Lung cancer is one of the most commonly diagnosed type of cancer and so it is fitting that we start the first of our disease-specific oncology series with this diagnosis. This week, we sit down with guest pulmonologist Dr. Greta Dahlberg to discuss how she thinks about and works up lung nodules concerning for malignancy.

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Lung nodules:

• For discussions about incidental lung nodules and lung cancer screening, check out episode 197 from our friends, The Curbsiders.

• Nodule vs. mass:

  • “Micronodule” is <3mm

  • “Nodule” is <3 cm

  • “Mass” is anything bigger

• Characteristics of “benign” vs. “malignant” nodule

  • Most important thing is change over time; therefore always good to have old imaging if possible.

    • If growing overtime, even if slowly, that should raise red flags for malignancy

    • Volume doubling time (link: https://radcalculators.org/volume-doubling-time-vdt-calculator-for-pulmonary-nodules-volume-based/)

      • If doubling time <20 days, it’s often infectious

      • Average lung cancer doubling times is 100 days

  • Benign:

    • Smooth

    • Calcifications (diffusely or popcorn calcifications)

    • Internal fat appearance

• What about a spiculated nodule?

  • This is when there are nodules with “little hairs” coming off, often thought to be malignant

  • Dr. Dahlberg reports that odds ratio of it being malignant is 2.5, so it is high, but not that high. So spiculated does NOT necessarily mean malignant.

• Workup:

  • Before referring to Pulmonary:

    • Dedicated CT scan of the chest

    • Obtain old imaging

    • PET CT

      • Expert tip: If growing, whether it’s hot or not, it warrants a biopsy

      • PET can help identify spread and/or nodal involvement

  • Biopsy approaches (we don’t know approach which one is better … There are studies ongoing!):

    • Transthoracic biopsy (CT guided):

      • Performed by IR

      • Major risk: pneumothorax (20-25% have one after procedure!)

      • Benefit: Does not need general anesthesia

    • Transbronchial biopsy:

      • Performed by Pulmonary

      • Requires general anesthesia and paralyzing

      • Options while doing biopsy:

        • EBUS

        • Fluoroscopy

      • Major risks: Pneumothorax (1.5% have one, less than half need chest tube)

      • Benefit: You can also do EBUS to stage mediastinum

        • Remember- we always look to upstage a cancer and by looking at the mediastinum, this helps to accomplish that

  • What if someone has two lung nodules on contralateral sides?

    • Likely both will be sampled

    • If PET has one nodule that is more FDG-avid than the other, they will go after that first. But they can sample both if safe.

  • Does PET help with bronchoscopy?

    • Can help, but appearance during bronchoscopy is more important

  • When is something NOT amenable to bronchoscopy?

    • The middle third of the lung is hardest and most technically challenging

    • Lower lobes of lungs, made difficult by atelectasis

    • Contrary to common belief, peripheral lesions are easier due to anatomy of the lungs

• About our guest: Dr. Greta Dahlberg is a pulmonary/critical care fellow at Vanderbilt University Medical Center in Nashville, TN. Thank you so much for joining us!

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