Carley Allison, 17, is seen at her Toronto home Monday, March 4, 2013. The student at Bayview Glen was recently diagnosed with a very rare one in a billion form of cancer. The aspiring singer/writer is using her music to create awareness. (Dave Thomas/QMI Agency)

Worrying about cancer is the last thing that should preoccupy a 17-year-old, but for Carley Allison, it is a stark reality.

Allison was recently diagnosed with a rare case of malignant melanoma outside her trachea.

What makes the cancer so rare is its location. With a one in one billion chance of a tumour growing next to her trachea, she is the seventh person in the world to fall prey to such a cancer.

“I was pretty upset, I just wanted it taken out of me,” the Grade 12 Bayview Glen student said from her North York home Monday.

Allison — a figure skater — experienced a bout of what she thought was asthma from exercising on Feb. 4. But results from a CT scan showed a tumour was growing which had left her with only two millimetres of airway in which oxygen could pass.