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Proton Therapy with Multimodality Treatment for Adenoid Cystic Carcinoma

 

In Fall 2018, a 35-year old woman was referred to Winship Cancer Institute of Emory University, an NCI-designated Comprehensive Cancer Center, after her community otolaryngologist had diagnosed an aggressive adenoid cystic carcinoma originating in the patient’s right parotid gland. Due to the cancer’s location near the facial nerve and propensity to travel along nerves, the surgeon recognized that she would require highly specialized care, including a powerful and precise tool for delivering radiation treatment.

Multidisciplinary Head and Neck Tumor Board

At Winship, the patient underwent evaluation and her case was reviewed by the multidisciplinary head and neck tumor board. The head and neck team recommended surgical resection of the adenoid cystic carcinoma with free flap reconstruction and facial nerve repair followed by postoperative radiation therapy.

Initial Head and Neck Surgeries

The Emory Head and Neck Surgical Oncology team, internationally known for expertise in skull base surgery, performed a radical parotidectomy with facial nerve sacrifice and a neck dissection. Because the facial nerve was involved by the tumor, the surgeon also drilled out a section of the temporal bone through which the facial nerve travels. This meant removing the nerve that controls facial movement and expression.

Without nerve repair, the right side of the patient’s face would have been completely paralyzed, leaving her unable to raise her brow, close her eye or smile. Additionally, she would have difficulty with speech, chewing, drooling, and self-expression.

After the resection was completed, the Emory Head and Neck Microvascular Reconstructive Surgical team took their place in the operating room. To restore the patient’s smile, the surgeon transferred one of the mastication nerves involved with chewing and jaw clenching, to the end of the remaining facial nerve branch involved in smiling.

To solve the loss of brow and eyelid functionality, a nerve allograft was utilized to span the gap from the remaining facial nerve trunk in the temporal bone to the facial nerve branches involved in eyebrow elevation and eye closure. All nerve repairs were performed using microsuture under a microscope.

Removing the cancer resulted in an 8 cm wide x 12 cm long soft tissue defect in the right face. The reconstructive team filled the soft tissue facial defect with a fat-containing free flap from her left thigh reconnecting the blood vessels from her thigh flap to blood vessels in her neck.

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MRI: (top) Enhancing tumor delineated in red, pre-surgery; (bottom) Complete resection of tumor and restoration of normal facial contour with free flap reconstruction

Over the next four months, as the nerve connections slowly regenerated, physicians saw the patient regularly. She also sent daily selfies on her own, showing off the steady improvement.

Proton Therapy in Multidisciplinary Care

After a few weeks of recovery from surgery, an important step in treatment remained. Virtually all non-metastatic head and neck adenoid cystic carcinomas are treated with radiation in order to eradicate any residual tumor cells and prevent the cancer from being able to travel along nerves to other parts of the body, such as the brain. The Emory Radiation Oncology team determined that the patient was an excellent candidate for proton therapy at the Emory Proton Therapy Center.

Proton therapy is a powerful and precise tool for delivering radiation treatment, allowing the radiation oncologist to precisely target the regions at risk of harboring residual cancer cells, including the facial and trigeminal nerves, thus maximizing the chance of optimal tumor control. Pencil beam scanning, available only at the newest proton therapy centers, allowed proton therapy to be delivered as small “spots” of radiation adjusted to the different depths and contours of the target.

Such precision meant less radiation spillover to normal tissues and consequently the potential for fewer short- and long-term side effects, which was very important given the location of the patient’s tumor and her young age. The Emory Proton Therapy Center team was able to reduce radiation to her salivary glands, to the delicate mucosa that lines the throat and mouth (extremely sensitive to radiation) and to the cochlea, optic nerves and brain stem. Her young age and long life expectancy meant potential benefits needed to be both short- and long-term.

To develop the best treatment plan, the radiation oncology team, including the center’s medical physicists and dosimetrists, used advanced software to carefully map out the target for radiation and developed a personalized treatment plan, calibrating each proton beam to optimally protect normal tissues. During treatment, a cone-beam CT was acquired to ensure the patient was properly aligned prior to each treatment session, and to monitor for any changes in internal anatomy or soft tissue that might necessitate adaptations in the treatment plan.

The patient received treatment at the Emory Proton Therapy Center five days per week for 30 treatments over six weeks total. She selected music and lighting to her preference and often fell asleep during the 20-minute sessions. To improve the chance of tumor control, the Medical Oncology team delivered weekly chemotherapy during proton therapy – in her case, carboplatin and paclitaxel.

Post-Proton Therapy Follow-Up

At three months post-radiation, an MRI showed no evidence of cancer recurrence. The repaired facial nerve is functioning well, providing tone around the eye and abroad, nearly involuntary smile, which she is especially pleased with. She reports no radiation side effects, has good saliva production, regular eating habits and normal taste. She has also returned to work with no long-term effects on her daily life and comes back to Winship at Emory every three months to see her physicians for surveillance.

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Image from patient’s proton therapy plan shows area treated with sparing of oral cavity and nontarget tissues

Emory Proton Therapy Center

The Emory Proton Therapy Center not only utilizes the most advanced radiation technologies and treatments but combines it with the expertise of renowned specialists at Winship Cancer Institute of Emory University. As the only National Cancer Institute (NCI)-designated Comprehensive Cancer Center in the state of Georgia, Winship discovers, develops and delivers some of the world's most effective ways to prevent, detect, diagnose and treat each patient's unique cancer.

To refer a patient, call 1-833-3PROTON (377-6866) or complete a referral form at
emoryhealthcare.org/protonreferral.

Emory Proton Therapy Center is committed to the continued health and safety of all patients. During this time, we are taking all necessary precautions to screen for coronavirus (COVID-19) and to prevent its potential spread. We continue to monitor the evolving COVID-19 pandemic and are working with experts throughout Emory Healthcare to keep your patients safe. For the most up-to-date information for our referring partners, click here.