Mona Passler Department of Gynecology, Competence Center for Ovarian Cancer (EKZE), Charité - University Medicine, Berlin 13353, Germany
A novel agent called checkpoint inhibitor therapy has revolutionized not only the treatment for several tumor entities but also our general understanding of oncology. As more and more patients with solid tumors undergo this promising immune therapy, new phenomena like pseudoprogression challenge the clinician. Pseudoprogression is a temporary increase in tumor size due to infiltrating leucocytes and edema during checkpoint inhibitor therapy, which can be mistaken with real progression. Subsequently, tumor size decreases due to tumor cell destruction. Pseudoprogression is described in 1,5% - 17% of all cases - depending on the tumor entity and study.
Identifying pseudoprogression plays a decisive part in successfully using checkpoint inhibition therapy, because the misinterpretation of tumor growth might lead to the discontinuation of an effective treatment, as pseudoprogression indicates a high likelihood of > 1year survival.
In order to guarantee the best possible treatment, it is crucial to be informed about pseudoprogression and to know techniques to distinguish between pseudo- and real progression when tumor size increases under checkpoint inhibition therapy. While there are several indicators to differentiate between the two, ultimately only infiltrating growth – which solely occurs in malign tumor growth – proves real progression.
