My father was diagnosed with stage-4 tongue cancer when I was 17. He recovered, and I still remember what a friend told me to help me through it.

• Two decades ago, when I was 17, my dad's tongue cancer was diagnosed.
• He needed aggressive treatment, including chemotherapy and radiation, for seven weeks.

I was 17 when I arrived home from school to find two cars in the driveway. I knew life was about to change.

My father, who should've been at work, met me in the doorway. "I have tongue cancer. Stage four," he said, "But I'm going to be OK."

My father's disclosure stung like alcohol on an open wound; his confidence was emptier than a deserted island.

I'm 39 now — a mother with two children of my own — but I still remember the words a friend offered in the days following my father's diagnosis: "Remember, it's the treatment making him sick, not cancer."

I thought my dad was going to die

My paternal grandmother had died from cancer two decades prior. That's what I knew about cancer at 17: It killed you. It multiplied faster than you could detect it, surreptitiously spreading from one organ to another. Within months of discovering cancer in her lungs and brain, she was gone.

When I heard the words "stage four" from my father, I crumbled. Nothing can prepare us for a loved one's journey with cancer. But my mother's friend's words of advice supported me through unprecedented times.

I reminded myself about the treatment all the time

My father was the stability in my childhood home. He remained calm when my mother and I couldn't — and during his treatment, that didn't change. I saw him as our strength.

When I saw him lying in bed instead of mowing the lawn or resting on the couch instead of washing the cars, I reminded myself he was fatigued from the chemotherapy and not from cancer. When his skin became red and irritated, I remembered that stemmed from the radiation and not the cancer itself. When swallowing became a chore and he got a feeding tube, I told myself this was a temporary phase in his treatment. And when I saw him after his lymph-node-removal surgery with tubes draining fluid from his neck, I remembered my mother's friend's words again.

This was all part of his treatment — every symptom was a sign of what was saving him. And it did.

Those words got me through

My dad survived. Now, 20 years later, he's the grandfather of my children, always with a joke to share and still capable of remaining calm through stress, a quality I'm continuously trying to adopt.

A diagnosis of stage-four tongue cancer meant aggressive treatment over seven weeks: radiation five days a week, chemotherapy once a week, and a neck-dissection surgery to remove lymph nodes with cancer cells. He's dealt with slowly progressive dysphagia, a difficulty swallowing, over the past two decades. But his story has a happy ending.

The final months of my senior year of high school weren't easy, but they would have been much darker had my mother's friend not offered those helpful words. I would've associated my father's struggling with a deterioration caused by cancer. I might have viewed manifestations of treatment as signs of sickness and reasons to worry instead of as part of a path toward renewed health.

She said the words I couldn't have found on my own and made perfect sense when nothing else did.