A 45 year-old woman with a history of metastatic carcinoid disease presented to our institution with progressive flushing and diarrhea.
She had been diagnosed with a carcinoid tumor 18 months earlier when an enlarged mesenteric lymph node was discovered incidentally during laparoscopic gastric bypass surgery. Pathologic evaluation demonstrated a moderately differentiated neuroendocrine tumor. Laboratory studies revealed an elevation in 24 hour urine 5 hydroxyindoleacetic acid (5HIAA) of 37.4 mg (reference range 1–6 mg) and an elevated serum serotonin of 1671 ng/ml (reference range 22–180 ng/ml). At the time of initial diagnosis, the patient denied any prior history of flushing, diarrhea or wheezing.
Magnetic resonance imaging of the abdomen revealed two hepatic masses, one in the dome of the liver measuring 6.8 cm, and another in the posterior right hepatic lobe measuring 2.2 cm. Indium-111-pentetreotide scintigraphy (OctreoScan™) revealed a focus of activity in the right hepatic lobe, as well as two foci of intense activity in the cardiac region (figure ). A primary gastrointestinal or bronchial tumor was not detected.
In-111-Pentetriotide Scan (OctreoScan) demonstrating a liver metastasis (block arrow) as well as two distinct tumors in the region of the heart (thin arrows).
Depot octreotide therapy was initiated, and a series of three laparoscopic hepatic radiofrequency ablations were performed over the ensuing 6 months. Although this therapy resulted in normalization of the 24-hour urine 5-HIAA, serum serotonin remained elevated (539 ng/ml). Moreover, the patient began developing progressive diarrhea and intense facial flushing despite dose escalation of depot octreotide from 30 mg to 60 mg every 4 weeks.
Repeat indium-111-pentetreotide scintigraphy twelve months after initial diagnosis demonstrated resolution of activity in the liver. However, persistent radiotracer uptake was detected in the region of the myocardium. Echocardiography was ordered to evaluate for the presence of cardiac metastases. It demonstrated trace to mild tricuspid insufficiency and trace aortic insufficiency, but showed no evidence of an intracardiac mass.
Magnetic resonance (MR) imaging of the chest was performed using multiplanar breath-hold, electrocardiogram-gated HASTE (Half Fourier Single Shot Turbo Spin-Echo) and electrocardiogram-gated, post-gadolinium T1-weighted spin-echo images obtained on a 1.5-Tesla Symphony MR scanner (Siemens Medical Systems, Malvern, PA). The MR images demonstrated a 3.8 × 2.1 cm mildly enhancing mass involving the free wall of the right ventricle as well as a poorly-defined mass involving the mid anterior left ventricular wall with extenstion to the apex. (Figure ). These masses correlated to sites of abnormal radiotracer accumulation on indium-111-pentetreotide scintigraphy (Figure inset).
Figure 2 T1 gated axial MRI image demonstrating mass in the right ventricular wall (long arrow) and more poorly-defined lesion in the left ventricular wall (block arrow) corresponding to sites of abnormal radiotracer uptake on indium-111-pentetreotide scintigraphy (more ...)
Consideration was given to surgical resection of the myocardial metastases, however, the risk of malignant arrhythmias was deemed prohibitive. Therefore, radiation oncology was consulted for external beam irradiation. A total of 45 Gray was delivered to the myocardium in 25 fractions using 3D-conformal technique (figure ). The patient's gross tumor volume (GTV) in both the right and left ventricles was drawn on the planning CT scans that had been taken with the patient in the supine position with her arms immobilized over her head in a vac-lok bag. The MRI images were used for aid in target volume delineation. Four beams consisting of an anterior superior oblique (ASO), anterior inferior oblique (AIO), left anterior superior oblique (LASO), and a right anterior superior oblique (RASO) were planned to deliver 45 Gy to the GTV + a 2 cm margin (figure ). Dose volume histogram (DVH) analysis showed that with this beam arrangement, <40% of the heart received the prescribed dose of 45 Gy, 60% of the heart received 30 Gy, and 50% received 40 Gy. 30% of the total lung volume received 20 Gy. 100% of the GTV received the prescription dose. Treatment was delivered using 18 MV photons with 60 degree wedges on each field. The therapy was complicated only by a brief episode of chest pain and dyspnea without electrocardiographic changes.
3-dimensional representation of fields with wedges.
Multileaf collimator treatment fields.
Repeat magnetic resonance imaging after completion of radiation demonstrated a fifty percent bidimensional reduction in the size of the right ventricular tumor (figure ) associated with a substantial decrease in serum serotonin levels to 205 ng/ml. Six months after treatment, the patient denied any chest pain, dyspnea or orthopnea and reported a moderate improvement in her facial flushing and diarrhea. Interferon α was added to octreotide therapy for further management of her metastatic disease.
Left ventricular mass before (5.a) and after (5.b) external beam irradiation.