explaination:
Skloot uses the phrase "by chance" to show Henrietta's uncanny fortune. It showed the serendipity of Henrietta's choosing to go to John Hopkins, because -- as luck would have it -- doctors were currently discussing what, exactly, qualified as cervical cancer, and if such a condition was found, how to treat it. It was as if she chose the perfect time in history to visit. The right people were there; the right topic was the current hot button; she was suffering from the right condition. She could not have been in a better place at a better time had she tried to be.