The European Organization of Research and Treatment of Cancer (EORTC) has recently developed and validated a patient-reported outcome measure (PROM) for sexual health (SH) in cancer patients. Here, we present results from a secondary analysis of the EORTC QLQ-SH22 validation study. The objective was to investigate the impact of cancer treatment on SH over the disease trajectory into survivorship in patients who underwent curative treatment.Participants completed the EORTC QLQ-SH22 and the EORTC QLQ-C30 assessing SH and Quality of Life. We analyzed differences in SH of patients on active cancer treatment compared to patients off-treatment (cross sectional group comparison) as well as changes in SH during the course of treatment (from pre-treatment to follow-up).Our sample consisted of n = 394 (66.2% females) curatively treated cancer patients with 34% of patients being on-treatment and 66% of patients being in their follow-up after primary treatment (off-treatment group). Compared to patients off- treatment, patients on active cancer treatment experienced less sexual satisfaction (p = .021, Cohen's d = .36) and libido (p < .001, d = .60) and had higher levels of fatigue (p < .001, d = .50). Importance of sexual activity, masculinity and femininity did not differ between groups. Treatment effects on sexual activity decreased with treatment completion (p < .001, d = .50). Patients undergoing intensified treatment (chemotherapy, radiation, or endocrine treatment) reported more treatment effects (subscale EORTC QLQ-SH22) compared to patients undergoing surgery only.Our results highlight the negative impact of oncological treatment on SH and how increasing treatment intensity further impair SH. Sexual satisfaction and libido improve after treatment completion while other aspects (e.g. masculinity/femininity) do not change during survivorship. We suggest monitoring of SH from the start of cancer treatment on and beyond into survivorship using PROMs as part of routine cancer care. Routine monitoring allows systematic identification of patient's SH problems and may improve awareness as well as target intervention for those in need of care.