Welcome back, everyone! We hope y'all had a wonderful summer, but I gotta say, we missed you fans. And we're ready for you to start experiencing the amazing Season 7. Let the fun begin...

In Episode 701, we meet nineteen-year-old Greg Bevell and his mother Donna. Greg suffers from a skull-based chordoma tumor... a BIG one at that. He arrived at the hospital in the E.R., having difficulty breathing, and April Kepner quickly brings Derek up to speed with Greg's scans. The tumor may appear so huge in size that initially it SEEMS inoperable, but this is Derek Shepherd. World-class neurosurgeon. He does not back down from a challenge. And now that he no longer holds the title of Chief of Surgery, he can devote all of his time and energy into giving Greg his best shot at survival...

What is a chordoma (and what makes them so daunting)?

A chordoma is a primary malignant bone cancer that develops from embryonic remnants that form the vertebral column. These types of tumors can be found anywhere along the spine, from the head to the tailbone, but the most common location tends to be at the top of the spine (in the clivus, a bone in the base of the skull) and the bottom of the spine (in the sacrum). When chordomas occur in the head, they can sometimes be called brain tumors, even though they do not form out of brain cells. And with being located in the skull, the tumors often touch or compress vital structures in the brain like nerves, arteries, the dura, and brainstem, causing a variety of different symptoms across the body.

In Greg's case, his chordoma began at the base of the skull, but when an earlier surgeon attempted removal, he broke the dura (the protective covering of the brain), allowing the tumor to "mushroom" down into the spine, wrapping around the cord.

What are the signs and symptoms?

The clinical and physical presentation obviously depends on the chordoma's location. But with intracranial masses, the most common symptoms include double vision and headaches. Other symptoms are neck pain and facial paralysis. If the tumor encroaches upon the spine, that invasion can cause changes in bowel and bladder function, aching, tingling, numbness, or weakness in the arms and legs. In Greg's case, due to the tumor wrapping around the brain stem, he also suffers from trouble breathing and maintaining blood pressure. If it had been allowed to continue to grow, it would have cut off the brain stem functions, and Greg would have died.

Who is at risk?

There are no known causes or risk factors. Chordomas can occur in people of all ages—from babies to the elderly; however, skull-base chordomas typically appear in younger patients. Families with multiple affected members have been reported, but it is still too rare to be considered actually hereditary.

In the United States, approximately 300 cases of chordoma are diagnosed each year. Therefore, researchers estimate that one new case is discovered per million people per year. Doctors have given an average survival rate of seven years, once diagnosed. Complete surgical resection offers patients their best hope at survival.

Treatment options

With this type of tumor, surgery is usually the first choice for treatment. Complete resection should be the goal because if tumor is still left inside the body, then recurrence remains a strong possibility (before seeing Dr. Shepherd, Greg had his tumor removed three times). Many surgeons also recommend radiation following surgery to maintain control, but sometimes the location limits the amount of radiation that can be delivered for fear of destroying vital tissue. Chemotherapy has not shown successful results in shrinking chordomas, and currently, no drugs have produced positive results.

Since Greg's chordoma was of such large size and in a tricky location, radical resection was the only option at this point... hence, Shepherd embarking on the incredible technique of splitting the entire lower face apart to excise the mass (a technique called the Le Fort osteotomy). In a Le Fort osteotomy, a procedure commonly used for facial surgeries, they split the hard palate, soft palate and separate the upper teeth from the face. This surgery was like that surgery on crack. Not only did they do a Le Fort osteotomy, they also split the jaw in half and cut down through the middle of the tongue. Then they divided the upper and lower teeth in half and hinged them out to the side. Essentially they were left with a large hole that provided access directly to the base of the skull (the clivus) where the tumor was (I personally cannot look directly at that surgery that we filmed in the OR, and I've seen the episode multiple times).

And though Greg will go through a tremendous amount of pain post-operatively, he will soon be able to begin the healing process, tumor-free, at last...