Yes, there were some studies with rats that showed a risk of bone cancer. I have not seen any research to back this up with humans. But the warning was on the Tymlos site, at least at one time.
https://tymlos.com/
Research:
" the initial phase 3 trials of the bone anabolic drug teriparatide were stopped because of a preclinical finding of osteosarcoma in rats treated with high doses of teriparatide for near lifetime. Even so, teriparatide was observed to reduce fracture risk in postmenopausal women with osteoporosis and showed efficacy and tolerability in the phase 3 program and in subsequent studies with a positive benefit to risk profile. Based on the phase 3 results, additional preclinical findings, and with risk mitigations, the agent was approved for use. Subsequent studies including in real‐world settings have not identified an increased risk of osteosarcoma in humans, and the label has been updated and adjusted, including removal of the boxed warning and a revision of the 2‐year lifetime limitation. Thus, observational studies with large sample sizes using real‐world data can be an important and efficient strategy for generating evidence in support of regulatory decision making and significant label updates."
https://pmc.ncbi.nlm.nih.gov/articles/PMC9465003/