My Dad had spinal and brain mets, and the docs wanted to try Topotecan, however they did radiation first, which lowered his platelet count to the point he had to wait 6 weeks for it to return to normal. By then, he was too sick to tolerate Topotecan (side effects are harsh).
The oncologist told me that with mets or SCLC recurrence, Topotecan would only prolong life by 26 weeks or less.