As a donor, that gave me pause. So I looked into what we do know.

In 2009, researchers found that there's "no evidence of increased cancer risk," though study participants had been followed for, on average, about four years.

Miller, who is also one of the study authors, says the latest data continues to indicate no increased risks from taking filgrastim for a PBSC donation.

Donating PBSC simultaneously enrolls you in an ongoing clinical trial to assess long-term risks and benefits.

Making the donation

Six months passed from the day Be The Match first contacted me to the day of donating. The timeline just depends on the recipient's health and treatment schedule.

Of course, there are lots of consent forms to sign, and a complete physical exam with a chest X-ray, EKG, and blood and urine samples before giving the green light for the donation.

The collection itself often requires traveling to another city, but everything from airfare and taxis to hotels and meals is paid for or reimbursed, for you and a companion.

My bone marrow harvest took about an hour. Doctors kept me in the hospital overnight, but not with regular hospital food. Ruth's Chris Steak House caters to marrow donors at my assigned hospital.

The next day I walked out, slowly and a bit sorely, with instructions to take it easy for two weeks as my body replaces the lost marrow.

Immediately after a bone marrow harvest, a volunteer courier travels -- by plane, train, or automobile -- with the stem cells and personally delivers them directly to the patient's location. At this point, the patient's abnormal bone marrow cells have already been intentionally destroyed by chemotherapy and/or radiation therapy, and the healthy stem cells are given to the patient through an IV drip.

Once infused, the stem cells automatically travel to the recipient's bone cavities and -- if the transplant is successful -- begin making healthy blood cells.

My recipient could be almost anywhere in the world: 51% of transplants through Be The Match involve an international donor or recipient. If we both consent, we can meet after at least one year, but either of us could choose to remain anonymous.

I hope to meet her.

I've created a fairly specific, though imaginary, image in my head of what she looks like, and the teary hug we would share.

Joining the registry is a statement: that when cancer affects one of us, it affects all of us.

All I know about my recipient is her age, diagnosis, and that she likely shares my English ancestry.

Minorities have lower chances of finding willing and able donors, as minority groups are not as well represented on the donor registry. For African-American patients, there's an estimated 66% likelihood of finding a donor.

The entrepreneur Amit Gupta, who was diagnosed in 2011 with Leukemia, was able to find a donor only after waging an online campaign encouraging more South Asians in the U.S. and abroad to join donor registries.

An average 54,000 people join Be The Match Registry every month.