Follow-up/Toxicity

Question 1

What is the typical f/u schedule of pts treated for lung cancer?

Answer 1

Typical lung cancer f/u: Stage I/II treated w/ Sg: H&P, CT chest with contrast q6mos yrs 1–3, then low-dose noncontrast CT chest annually yrs 3–5. Stage III or treated with RT: CT chest with contrast q3–6 mos for yrs 1–3, then q6 mos for yrs 4–5, then low-dose noncontrast CT chest annually. Continued smoking cessation counseling for all. (per NCCN 2018)

Question 2

What are the expected acute and late toxicities of RT for lung cancer?

Answer 2

1. Acute: Skin reaction, fatigue, dysphagia, odynophagia, cough
2. Subacute and late: RT pneumonitis, lung fibrosis, brachial plexopathy, Lhermitte syndrome, RT myelitis, esophageal fibrosis/stricture, pericarditis, 2nd cancers

Question 3

What are the signs and Sx of RT pneumonitis, and how is it managed?

Answer 3

RT pneumonitis is a subacute reaction that begins as early as 3–6 mos after RT. Typically, Sx include chest pain, shortness of breath, fever, and hypoxia. CT scan shows ground glass changes within the RT port. Check oxygenation and supplement if necessary. If symptomatic, treat with prednisone 1 mg/kg/day for at least 3 wks with a very slow taper. Bactrim can be used for PCP prophylaxis.

Question 4

What is the total lung V20 dose-volume constraint for RT alone and concurrent CRT in definitive lung cancer Tx?

Answer 4

1. NCCN: V20 <37%

2. MDACC: RT alone → V20: <40%; CRT → V20: <35% (based on Lee HK et al., IJROBP 2003)

Question 5

What is the mean lung dose (MLD) constraint for definitive RT to lung cancer?

Answer 5

MLD ≤20 Gy.

Question 6

What is the heart RT dose-volume constraint?

Answer 6

1. NCCN 2018: V40 ≤80%, V45 ≤60%, V60 ≤30%; Mean ≤35 Gy
2. MDACC: RT alone → V40: <50%; CRT → V40: <40%

Lower dose exposure may also be important: RTOG 0617 also found that increased heart V5 and V30 were associated with inf OS on MVA.

Question 7

What is the dose constraint for the brachial plexus?

Answer 7

The dose constraint is 1 cc below 60 Gy; the max dose point should be <66 Gy. 2 retrospective studies showed that the dose could be higher. (MDACC, Amini A et al., IJROBP 2012; median dose >69 Gy, max dose >75 Gy to 2 cc; and UPenn, Eblan MJ et al., IJROBP 2013: V76 <1 cc)

Question 8

What is the max esophageal dose?

Answer 8

Ideally, MLD <34 Gy. Try to minimize the V60 as much as possible (V60 <33%, V50 <50%, ≤45 Gy to the entire esophagus, max dose point <70 Gy).

Question 9

What is the expected grade 3–4 esophagitis rate in pts treated with sequential CRT vs. concurrent CRT in locally advanced NSCLC?

Answer 9

(Choy H, ASTRO 2003 [summary of multiple studies])

Sequential: ∼4%

Concurrent: ∼22%

Question 10

What are the strategies for delivering external RT to lung tumors if dose constraints cannot be met?

Answer 10

1. Induction chemo for debulking
2. Breath-hold
3. IGRT (e.g., daily CBCT to decrease PTV margins)
4. Adaptive planning during Tx
5. Alternative modalities (i.e., protons)
6. Sequential chemo → accelerated hypofractionated RT (45 Gy in 15 fx)