I worked in heme-onc for almost five years. I can't say whether heme-onc is med-surg on steroids because I've never worked in med-surg but we were taking care of primarily step-down-type hematology patients on a tele floor, so there were a ton of medications (almost all IV), ton of infusions (chemo, immunotherapy), symptom management. Also on our floor we took care of the more "stable" vents, managed tube feedings, cardiac drips--you name it. The only things we did not do were auto or allo transplants.
To answer dianearc's questions, if you want to get pregnant, then chemotherapy is a concern, of course, but not so much before getting pregnant--otherwise, half of the RNs wouldn't be able to work. The minute someone finds out they're pregnant, however, they should tell someone. I think back issues would go with any unit, not just heme-onc. On my unit, day shift had a 3:1 ratio unless we were severely short-staffed, sometimes (rarely) 2:1 depending on what was going on with the patient.