PURPOSE Cancer survivors experience better outcomes when primary care providers (PCPs) are engaged in their care. Nearly all survivors have a PCP engaged in their care in the initial 5 years postdiagnosis, but little is known about sustained PCP engagement. We assessed PCP engagement in survivors' care 5-7 years postdiagnosis and characterized survivors most vulnerable to loss to PCP follow-up. METHODS We linked electronic health record ambulatory care and cancer registry data from an National Cancer Institute–Designated Comprehensive Cancer Center to identify eligible survivors (≥18 years; diagnosed with breast, colorectal, or uterine cancer; had an in-network PCP). We used multiple logistic regression to assess associations between survivor demographics, clinical factors, and health care utilization and odds of sustained PCP engagement. RESULTS In 5-7 years postdiagnosis, PCPs were engaged in care for 43% of survivors. Survivors with sustained PCP-engagement were on average 4.6 years older than those without ( P < .0001); survivors had 1.36 greater odds of having regular PCP visits for each decade increase in age on cancer diagnosis ( P = .0030). Survivors were less likely to be lost to PCP follow-up if diagnosed at an earlier stage with odds at 0.57 and 0.10 for stage I and stage IV, respectively ( P = .0005), and had 2.70 greater odds of engagement in care with at least one oncology visit annually 5-7 years postdiagnosis ( P < .0001). CONCLUSION Sustained PCP engagement is endorsed as critical by survivors, PCPs, and oncologists. We found most survivors were lost to PCP follow-up 5-7 years postdiagnosis. Our study is among the first to contribute empirical evidence of survivors being lost in transition. Findings from this study demonstrate the need to bridge gaps in long-term care for cancer survivors.