Timothy M. Zagar, M.D.October 19, 2015

Prospective Assessment of Deep Inspiration Breath Hold to Prevent

Radiation-Associated Cardiac Perfusion Defects in Patients with

Left-Sided Breast Cancer

Disclosures• VisionRT

Background• RT-associated cardiac disease is real

• Patients die from this

• Clinically relevant cardiac damage takes years to manifest– Not necessarily decades as previously

thought

Darby SC, et al. N Eng J Med 368:987-998, 2013 Cuzick J, et al. Cancer Treat Rep 71:15-29, 1987

The Oxford Review• 42,000 patients from 78 randomized

trials– 23,500 RT versus no RT

• The use of RT improved LC, BCSM and OS

• However, there was an increased risk of non-cancer mortality in RT patients, primarily from:– Heart disease: RR 1.27

EBCTCG Lancet 366:2087-2106, 2005

Bentel, Marks, Hardenbergh, Prosnitz, IJROBP 44:1017, 1999

Harvard JCRT. J Cardiovasc Magn Reson 2002;4:265-71

Exhalation Deep Inspiration

Deep Inspiration

Moves the heart inferiorly & posteriorly

DIBH allows:

•Decrease Heart Dose

•Reduces Tumor Bed Motion

•Decreases Lung Dose

Tangent Fields

How do we image cardiac defects?

• Nearly 50% of patients had a perfusion defect at 6 months

• Though significance of perfusion defects is unclear Marks LB et al IJROBP 63:214-223, 2005

How to limit cardiac dose?

• Heart Block

• DIBH– VisionRT®, RPM (Varian®), ABC

(Beaumont)

• IMRT– Resultant increase in low dose bath

Heart Block Examples

Heart Block

Midline

Marks IJROBP 1994

May miss breast tissue under heart block

Methods• Left-sided breast cancer pts were

enrolled on an IRB-approved, single-arm prospective clinical study to assess DIBH

• Each patient received a pre-RT SPECT-CT rest-cardiac gated perfusion scan

• All patients received tangential radiation to the breast/chest wall. Typical doses: 2 Gy x 25 fractions or 2.67 Gy x 16 fractions

Methods• To design the RT plan, DIBH and

conformal blocking was used to assure that the heart was excluded from the primary RT beam

• At six months port-RT, the SPECT-CT was repeated

• The perfusion and motion images were assessed qualitatively by a nuclear medicine physician

Results• Twenty-five patients enrolled; four

were not evaluable due to abnormal pre-RT SPECT scan, one was lost to follow-up

• Of the 20 evaluable patients, all completed the tangential radiation course; five also received regional nodal RT as well; and 18/19 received a tumor bed boost

Results• The mean heart dose ranged from

42-160cGy for the 20 patients. Mean of the mean heart dose over all patients was 78 cGy

• Six month follow-up SPECT scans have been obtained for 14 patients, to date

• All 14 have a normal post-RT SPECT scan; and/or no change from pre-RT cardiac perfusion status

Discussion: Must be mindful

57 womenStage I-III L breast cancer

SPECT

DIBH RT

Standard breast RT SPECT

SPECT

Zellars RC et al. Int J Radiat Oncol Biol Phys. 2014 Mar 15;88(4):778-85

Hopkins Randomized• Despite randomization, DIBH pts more

likely– To be younger (median age 51 vs. 62)– To have received chemotherapy (52% vs. 18%)

• Pts treated with DIBH had MORE cardiac apical perfusion defects– Perhaps not as reproducible– Dr’s may have been too tight on their heart

block• Though significance of perfusion defects is

unclear (repeat)Zellars RC et al. Int J Radiat Oncol Biol Phys. 2014 Mar 15;88(4):778-85

Conclusions• DIBH treatment techniques are well-

tolerated by most breast cancer patients

• Mean dose to the heart can be reduced using DIBH techniques

• Cardiac avoidance with DIBH appears to be able to prevent the development of RT-associated cardiac perfusion abnormalities