Cancer is a word you never want a doctor to say to you. When you're older, it's traumatic enough, but when you're young and still thinking about your whole life and future family, it is devastating.
A friend of mine in high school was diagnosed with Hodgkin's lymphoma as a college freshman. She dropped out of school and underwent surgery and chemotherapy. She is now in her 40s and has three children.
Of course, they told her that her chemotherapy may make it hard or even impossible for her to have children. As a result, she was rather careless, and was surprised to find herself pregnant just two years after completing chemotherapy!
It is true that chemotherapy can adversely affect your fertility as a woman because women are born with all their eggs. Less so for men because sperm are made all the time, but sometimes chemotherapy can destroy the sperm-making cells. Today, a young woman is likely to be offered the opportunity for egg harvest and freezing, and men will also store sperm. For women, the best odds are still to fertilize the eggs and freeze the resulting embryos, but egg freezing is an option. If you have enough eggs harvested, do both. Younger women are likely to retrieve many eggs, giving them a good chance later on to have a family.
Essentially all chemotherapy drugs and radiation are potentially hazardous to eggs. Definitely chemotherapy during pregnancy is not possible as most chemotherapy targets rapidly-dividing cells, which is exactly what a developing fetus is doing.
The advantage of frozen embryos is that once you have them, you can unfreeze and transfer them at any time, making your age less relevant. For some women with breast cancer, continued treatment with drugs like tamoxifen prevent them from getting pregnant. They may need to use a surrogate to have their own children.
Egg harvesting offers a young woman hope and something to dream about while going through cancer treatment. We have come a long way with treating cancer, and there is every reason to believe that you, if given a cancer diagnosis, will survive. After all that, having a baby will be even more special!