Radiation-induced cardiomyopathy as a function of radiation beam gating to the cardiac cycle

Dose-Dependent Radiation-Induced Myocardial Damage in Esophageal Cancer Treated With Chemoradiotherapy: A Prospective Cardiac Magnetic Resonance Imaging Study

PURPOSE

The purpose of this prospective study was to evaluate radiation-induced myocardial damage after mediastinal radiation therapy (RT) using late gadolinium-enhancement (LGE) magnetic resonance imaging (MRI).

METHODS AND MATERIALS

We enrolled 19 patients with esophageal cancer who were expected to have long-term survival by definitive treatment. They underwent delayed contrast-enhanced MRI (19 patients before treatment, 19 patients 6 months after treatment, and 12 patients 1.5 years after treatment). Dose distribution of the left ventricle was made using computed tomography, and the dose volume histogram of the left ventricle was calculated. Myocardial signal intensities in individual MRIs were normalized by the mean values in regions receiving low doses (<5 Gy). Changes in the normalized signal intensities after mediastinal radiation therapy were compared among regions where irradiation doses were 0 to 10 Gy, 10 to 20 Gy, 20 to 30 Gy, 30 to 40 Gy, 40 to 50 Gy, and 50 to 60 Gy, and we investigated whether intensity change was detected in a dose-dependent manner.

RESULTS

The registered patients were treated with concurrent chemoradiotherapy with a median total dose of 60 Gy (50.4-66 Gy). Chemotherapy consisting of cisplatin and 5-fluorouracil was administered. In the population-based dose-response curve, dose-dependent intensity changes progressively increased in regions receiving more than 30 Gy. The averages of relative intensity change at 6 months and 1.5 years after treatment were 1.1% and -1.9% at 20 to 30 Gy and 37.5% and 17.5% at 40 to 50 Gy, respectively. LGE in regions receiving more than 30 Gy was detected in 68% (13/19) of the patients.

CONCLUSIONS

A dose-dependent relationship for myocardial signal intensity change was found by using LGE MRI. It may be necessary to reduce the volume of the myocardium receiving more than 30 Gy.

Radiotherapy is effective for a primary lung cancer invading the left atrium

Atrial involvement is an uncommon feature of advanced non-small-cell lung cancer, occurring in up to 10% of patients with bronchogenic carcinoma. Additionally, cardiac metastases from other sources are documented in up to 7% of cancer patients at autopsy. Because atrial invasion can lead to systemic embolisation and/or outflow obstruction, it is treated regardless of the overall prognosis. While the gold standard treatment has historically been surgical resection, advances in radiotherapy allow for the safe treatment of cardiac disease. Here we present the case of a woman with pulmonary adenocarcinoma of the left lower lobe that progressed to invade the pulmonary vein and left atrium while maintained on standard chemotherapy. She was treated with intensity-modulated radiotherapy and had a complete response in terms of her atrial disease within 3 months. She suffered no acute toxicity or complications as a result of the radiation therapy.

Acute left bundle branch block as a complication of brachytherapy for lung cancer

Endoluminal brachytherapy for lung cancer ensures the delivery of a maximal therapeutic radiation dose to the tumor with a minimal effect on normal surrounding tissues. We report on a 62-year-old man, who acutely developed LBBB and heart failure 48 hours after the second course of combined endoluminal and external beam radiation therapy. After administration of angiotensin converting enzyme inhibitors, diuretics, and anti-inflammatory drugs, electrocardiographic changes resolved and patient completely recovered. Radiotherapy was reintroduced after ten days.

Successful radiation treatment of anaplastic thyroid carcinoma metastatic to the right cardiac atrium and ventricle in a pacemaker-dependent patient

Anaplastic thyroid carcinoma (ATC) is a rare, aggressive malignancy, which is known to metastasize to the heart. We report a case of a patient with ATC with metastatic involvement of the pacemaker leads within the right atrium and right ventricle. The patient survived external beam radiation treatment to his heart, with a radiographic response to treatment. Cardiac metastases are usually reported on autopsy; to our knowledge, this is the first report of the successful treatment of cardiac metastases encasing the leads of a pacemaker, and of cardiac metastases from ATCs, with a review of the pertinent literature.

Risk factors for pericardial effusion in inoperable esophageal cancer patients treated with definitive chemoradiation therapy

PURPOSE

To identify clinical and dosimetric factors influencing the risk of pericardial effusion (PCE) in patients with inoperable esophageal cancer treated with definitive concurrent chemotherapy and radiation therapy (RT).

METHODS AND MATERIALS

Data for 101 patients with inoperable esophageal cancer treated with concurrent chemotherapy and RT from 2000 to 2003 at our institution were analyzed. The PCE was confirmed from follow-up chest computed tomography scans and radiologic reports, with freedom from PCE computed from the end of RT. Log-rank tests were used to identify clinical and dosimetric factors influencing freedom from PCE. Dosimetric factors were calculated from the dose-volume histogram for the whole heart and pericardium.

RESULTS

The crude rate of PCE was 27.7% (28 of 101). Median time to onset of PCE was 5.3 months (range, 1.0-16.7 months) after RT. None of the clinical factors investigated was found to significantly influence the risk of PCE. In univariate analysis, a wide range of dose-volume histogram parameters of the pericardium and heart were associated with risk of PCE, including mean dose to the pericardium, volume of pericardium receiving a dose greater than 3 Gy (V3) to greater than 50 Gy (V50), and heart volume treated to greater than 32-38 Gy. Multivariate analysis selected V30 as the only parameter significantly associated with risk of PCE.

CONCLUSIONS

High-dose radiation to the pericardium may strongly increase the risk of PCE. Such a risk may be reduced by minimizing the dose-volume of the irradiated pericardium and heart.

Rates of myocardial infarction and coronary artery disease and risk factors in patients treated with radiation therapy for early-stage breast cancer

BACKGROUND

Radiation therapy (RT), a critical component of breast-conserving therapy for breast cancer, has been associated with coronary artery disease (CAD) in numerous older studies, but the risk may be lower with modern techniques.

METHODS

Observed rates of cardiac events in 828 patients treated with breast-conserving surgery and RT at the University of Michigan were compared with expected rates. Relations between potential risk factors and actuarial rates of first CAD event were analyzed.

RESULTS

Observed risks of cardiac events were lower than expected. The standardized incidence ratio (SIR) of myocardial infarction (MI) was 0.44 (95% confidence interval [CI]: 0.21-0.70). The SIR of MI or CAD requiring intervention was 0.50 (95% CI: 0.27-0.68). With a median follow-up of 6.8 years, 12 (1.4%) patients had at least 1 MI on follow-up and 20 (2.4%) had at least 1 MI or CAD requiring intervention. Median age at first cardiac event was 75.9 years (range, 43.1-91.5). Median interval from RT to occurrence of the first cardiac event was 3.7 years (range, 13 days to 15.4 years). The 10-year cumulative incidence of MI was 1.2% and cumulative incidence of MI or CAD requiring intervention was 2.7%. On multivariate analysis, age, diabetes mellitus, active smoking, and laterality of RT were significant predictors of MI. Age and active smoking were significant predictors of MI or CAD requiring intervention.

CONCLUSIONS

Patients in this series had lower risk of ischemic cardiac events than expected. Although small in absolute magnitude, patients radiated to the left side did have a statistically significant increased risk of MI. These findings support further investigation of techniques to minimize the long-term cardiac risks faced by breast cancer patients.

Reduction of organ motion by combined cardiac gating and respiratory gating

PURPOSE

To investigate whether the effect of organ motion can be further reduced with the application of a cardiac gating technique, together with respiratory gating.

METHODS AND MATERIALS

Axial and coronal images through the heart and liver were continuously scanned with fast cine magnetic resonance imaging scans at three different gating settings: (1) without respiratory and cardiac gating; (2) with respiratory gating, but without cardiac gating; and (3) with both respiratory and cardiac gating. The effect of motion for either the heart or liver was analyzed with probability maps.

RESULTS

With the application of respiratory gating only, the marginal region on the probability map was reduced by 10.0% in the axial slice and 19.8% in the coronal slice for the heart. It was reduced by 5.2% in the axial slice and 20.8% in the coronal slice for the liver. With the application of cardiac gating together with respiratory gating, the marginal region on the probability map was reduced further. The reduction was 8.0% in the axial slice and 13.6% in the coronal slice for the heart and 5.9% in the axial slice and 7.0% in the coronal slice for the liver.

CONCLUSION

The effect of organ motion can be further reduced with the application of cardiac gating together with respiratory gating. The potential application to treatment planning merits further investigation.

Is There an Increased Risk of Local Recurrence Under the Heart Block in Patients with Left-Sided Breast Cancer?

Tangential radiotherapy for left-sided breast cancer may be cardiotoxic. Shaping the field with a heart block reduces cardiac exposure but may under-dose the breast and/or chest wall. We compared the incidence and location of local recurrences in patients irradiated with and without a heart block.

METHODS AND MATERIALS

Between 1994 and 1998, 180 patients irradiated to the left breast and/or chest wall were retrospectively reviewed. The local recurrence rates in patients treated with and without a heart block were compared using a 2-tailed Fisher exact test. An in-depth dosimetric analysis was performed in 23 patients to assess the percentage of breast tissue under-dosed by inclusion of the heart block.

RESULTS

Overall, the local recurrence rates in patients with or without a heart block were similar. In postlumpectomy patients with inferiorly located tumors, the rates of local recurrence with and without a heart block were 2 of 6 patients versus 0 of 19 patients, respectively. In the dosimetric analysis, the average percentage of breast tissue under-dosed by the inclusion of a heart block was 2.8% (range, 0%-11%).

DISCUSSION

A heart block is a reasonable method to limit cardiac dose but should be used cautiously following a lumpectomy in patients with inferiorly located tumors. Additional study with larger numbers of patients is warranted.