Lung Metastases and DTC
A medical professional explains how the size of lung metastases affect the treatment of DTC and clinician decision-making.
Marcia S. Brose, MD, PhD: The size of the metastasis affects my treatment and my thinking as far as when I’m going to start treatment. The reason for that goes back to the question of tumor burden. If I have lesions that are very large, even if they shrink in half, they’re still going to be quite large. In the process of shrinking, all that extra tissue that’s slopped off could cause symptoms. I’ve had patients who had quite a bit of disease. When they started killing that disease with lenvatinib, they had a severe cough that lasted for 2 to 4 months until it finally calmed down. The size of the lesion matters because it’s a question of the overall tumor burden. There are people, however, who have a solitary nodule that’s 2 cm and not doing them any harm. Size by itself is not going to be the only thing with treatment decision-making.
Alternatively, some patients have millions or hundreds of thousands of small—what we call miliary disease, where all the lesions are about 1 mm big, but 50% of their tumor bind is taken up by this miliary disease. Clearly, you can’t wait for those to get larger, but those are the patients who will benefit the most from starting on disease. There was an interesting study by [Makoto] Tahara et al, presented at ESMO [European Society for Medical Oncology Congress] in 2019, that looked at the differences of size and showed that people who had a bigger size did better overall, as far as getting treated with lenvatinib. They’re selecting for patients who have more advanced disease and more progressing disease but by itself is not a criterion. It feeds into the criteria I described before, which has to do with the number of lesions, the size of them, and those contributed to tumor burden. But remember, there are things that are not size dependent, such as if they have symptoms, or what’s the location, which is not size dependent but is more of a risk evaluation that needs to be made. Size matters. It was shown to matter. It goes into our decision-making, but it doesn’t encompass all the aspects that I’m going to use to evaluate when to start a patient on treatment.
This transcript has been edited for clarity.
Case: A 70-Year-Old Woman With Differentiated Thyroid Cancer
Initial presentation
- A 70-year-old woman presents with a painless “lump on her neck.”
- PMH: unremarkable
- PE: palpable, non-tender solitary right-of-the midline neck mass; otherwise unremarkable
Clinical workup and initial treatment
- Labs: TSH WNL
- Ultrasound of the neck revealed a 3.4 cm suspicious right mass arising from the right thyroid; 4 suspicious supraclavicular lymph nodes (LNs), largest 2.2 cm in size.
- Ultrasound-guided FNAB of the thyroid mass and the largest LN confirmed papillary thyroid carcinoma.
- Patient underwent total thyroidectomy with central compartment and right selective neck dissection.
- Pathology: 3.4 cm papillary thyroid cancer arising in the right lobe of thyroid, tall-cell features; extrathyroidal extension present;
- 2 of 6 positive central compartment lymph nodes, largest 1.8 cm
- 4 of 13 right lateral compartment involved nodes largest 2.2 cm in size, positive extra nodal extension.
- StageT2N1aMX; ECOG PS 0
Subsequent treatment and follow-up - She was treated with radioactive iodine 150 millicuries
- Whole body scan showed uptake in the neck, consistent with thyroid remnant but no uptake in the lungs
- Follow-up at 3 months
- TSH 0.2 µU/mL, thyroglobulin 28 ng/mL (negative anti-thyroglobulin antibodies)
- Chest CT scan showed 8 small bilateral lung nodules largest 1.3 cm
- Follow-up CT neck and chest scan 3 months later was notable for 1-2mm growth in several lung nodules and 3 new distinct 9.5 mm lung nodules
- Next-generation sequencing was negative for mutations, rearrangements
- Lenvatinib 24mg po qd was initiated
Case 2: A 57 Year-Old Man With Differentiated Thyroid Cancer
Initial presentation
- A 57-year-old man presents with a solitary nodule on the neck and occasional shortness of breath and intermittent excessive fatigue
- PMH: unremarkable
- PE: palpable, hard and fixed solitary nodule in the anterior neck
Clinical workup and initial treatment
- Labs: TSH 10.3 µU/mL; all others WNL
- Ultrasound of the neck revealed a 2 cm mass near the isthmus of the thyroid; several suspicious lymph nodes ranging from 0.3-2.4 cm in size
- Ultrasound-guided FNAB: confirmed papillary thyroid carcinoma; with nuclear enlargement and nuclear grooves, no colloid seen
- Patient underwent total thyroidectomy with bilateral central neck dissection
- Pathology: 2.1 cm papillary thyroid cancer arising in isthmus of the thyroid, 3 of 7 positive central compartment lymph nodes, largest 1.8 cm, positive extra nodal extension
- StageT2N1MX; ECOG PS 1
Subsequent treatment and follow-up
- He was treated with radioactive iodine 150 millicuries
- Whole body scan showed uptake in the neck; indicative of thyroid remnant
- Follow-up at 3 months TSH 0.2 µU/mL, thyroglobulin 68 ng/mL
- Neck US showed no evidence of residual disease in thyroid bed, no suspicious neck nodes. Chest CT was done: 4 lung lesions that were 0.3 and 0.6 cm in size
- The physician recommended not initiating systemic therapy and putting the patient on active surveillance
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