Hopatcong has rallied around 11-year-old Kyle O'Brien. From dunk tanks to get well cards to professional soccer stars donating time, the people have organized fundraisers to help him fight juvenile pilocytic astrocytoma.

But what exactly is that? Here are 5 Things You Need to Know About juvenile pilocytic astrocytoma, according to health.com.

You Need to Know It's Rare: Juvenile pilocytic astrocytoma is a rare childhood brain tumor. Most of these tumors are benign and don't spread to the brain tissue. Kyle's is located on his brain stem.

You Need to Know Its Symptoms: Depending on the size and location, the tumors symptoms may vary. Common symptoms are headaches, loss of balance, vision distortion, vomiting and nausea as a result of increased brain pressure.

You Need to Know Where It Spreads: Juvenile pilocytic astrocytoma often develops from gilal cells, consisting of star-shaped brain cells called astrocytes, which form tissue protecting other nerve cells found within the brain and spinal cord.

You Need to Know How Long Kyle's Had It: He was diagnosed at age 8 despite doctors' first diagnosis: bad allergies.

You Need to Know How He's Fighting It: Kyle and his family have traveled to the Children's Hospital of Philadelphia for proton radiation therapy, which precisely localizes radiation dosages to erradicate diseased tissue.