The conducted survey reflects the complex and heterogeneous condition of resident formation in Germany concerning hematological malignancies. It demonstrates that 1) the majority report an overall competence to treat hematological malignancies which is good to moderate, but this assessment differs remarkably between the participants; 2) although most participants claim that their hospital/private practice treats lymphoma and leukemia patients on a regular basis, patient numbers are low, and that 3) this is especially true for pediatric patients and special techniques like total-skin irradiation and proton treatment; 4) there is an unmet need for more competence-based and interactive teaching formats.

Comparing the German participants’ experience with those of the American ARRO survey reveals similarities and differences. Whereas the German participants reported a lack of experience with proton therapy in 87.1% of the cases, only 68.6% of the ARRO participants did. Particularly, 30.3% of the American participants even reported a patient number treated with protons exceeding 10, suggesting that proton therapy plays a greater role in the United States, both in treatment and in resident training. Apart from that, the German participants claimed to be better prepared or to have a higher level of experience concerning many aspects of hematologic malignancies: 27.9% of the German participants reported a higher number of adult patients ( 7 or more) treated with craniospinal axis vs. 8.7% of the American participants. Overall, 41.5% of the German participants felt well or very well prepared for the treatment of leukemia and lymphoma, compared with only 26.9% of the ARRO participants.

Although less common than solid tumors, lymphoma and leukemia are still an integral part of the standard curriculum for board certification in RO, both in the present [6] and in the upcoming new licensing regulations [13]. The latter represents a shift from mere knowledge acquisition to competence-based education focusing on practical skills. This evolution challenges established teaching practices and aims to involve students (and latter residents) more actively. Concerning RO, examples of new teaching formats have been presented which are establishing a link to basic subjects (anatomy, physiology) [14], deepening the understanding of brachytherapy [15] or introducing digital concepts [16]. Correspondingly, Linde et al. elaborated a desire for practical education and early integration of RO in the curriculum amongst medical students [17]. Knowledge should be deepened and extended in the respective specialty areas during resident formation. However, data from surveys conducted by the youngDEGRO suggest that hematological malignancies are only taught in a minority of medical faculties (41.7%), with a resulting bad to mediocre resident knowledge [4, 11].

A particular lack of expertise is evident for pediatric patients, as 46.9% and 57.1% of all contributors have never participated in the treatment of a craniospinal irradiation or TBI in children, respectively. The latter figure is worrisome, as TBI was shown to be a superior conditioning modality for pediatric patients with acute lymphoblastic leukemia in comparison to a chemotherapy-only strategy in the randomized FORUM trial [18]. At the same time, pediatric patients are vulnerable to radiation effects, with an increased rate of secondary malignancies after TBI [19]. Thus, critical evaluation and discussion of both the efficacy and toxicity of radiation treatment (by well-trained board-certified radiation oncologists) is needed. Likewise, some techniques like proton therapy are only available at sparse specialized centers, explaining the lack of expertise here.

Only 30–50% of participants reported feeling that they have good or very good knowledge of the correct specification of planning CT and target volume definition. Interestingly, reported confidence numbers declined when contouring according to the principles of ISRT is demanded in comparison to a contouring in general. This suggests that at least some participants tend to define target volumes for lymphoma in a non-structured way. This is surprising in the light of several contouring and treatment guidelines provided by the International Lymphoma Radiation Oncology Group [20,21,22,23].

The survey conducted has several limitations. Due to the voluntary participation, the response rate is incomplete. Furthermore, it is likely that particularly motivated residents or those working at a specialized center were more likely to respond. Considering this selection bias, the overall situation is likely worse, and the results may not be representative for the federal situation. To increase the participation rate, future surveys should be conducted on multiple platforms, also including social media, and should be highlighted with reminders/direct links to the questionnaire during the annual meeting of DEGRO. Additionally, the questionnaire relied on self-assessment only, without asking for external assessment by those responsible for training organization (senior physicians, head of departments) or considering objective outcomes (results of board certification, scientific abstracts, or papers on hematological malignancies).

Nevertheless, the data presented are a valuable addition to the overall picture of the educational situation in Germany. As only two national societies in radiation oncology have surveyed their hematological resident formation so far, more evaluations will have to be performed for a global or at least multinational perspective.

Future developments must address resident formation on multiple levels. Interactive workshops, digital courses, or tumor boards may help to broaden knowledge and practical treatment skills for lymphoma. To enable sufficient patient numbers for these entities, a rotation program may be useful; this has already been implemented by the youngDEGRO. As participant numbers increase after the COVID-19 pandemic, evaluation results of this effort are eagerly awaited. Together with the reference radiation oncologists of the German Lymphoma Alliance and German Hodgkin Study Group, these efforts will aim to broaden and deepen resident knowledge of modern radiation oncology treatment for leukemia and lymphoma. In the end, generating and maintaining radiation oncology expertise in hematological malignancies will be essential to develop personalized treatment strategies for the individual patient.