Perspectives on Mail-Based Fecal Testing for Colorectal Cancer Screening in Bulgaria: A Survey of Gastroenterologists

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

A well written study by the authors and a topic of great interest and importance to not only gastroenterologist but also to all healthcare providers.  Any form of research or intervention that helps screen patient's for cancer and prevent it from occurring deserves evaluation.  It is well established that colonoscopy is the standard form of colorectal cancer screening that is actually preventative as all the other modalities of colon cancer screening require follow up with a colonoscopy if they are positive to ensure that colon cancer is prevented.  However a colonoscopy itself carries significant barriers in certain parts of the world and also in certain populations given limited resources as well as the financial constraints that accompany this.  It is not surprising as shown in the study that the fecal occult blood test had great support by the gastroenterologist as a screening test.  Being able to do a mail based FOBT would certainly augment compliance and also successful completion of the test.  The study design is outlined clearly and describes how they conducted their survey.  The results are reported not only in text but also as a table formulation.  The authors have also included a bar graphs that helps add further insight into their study with the perceived barriers to screening.  Apart from that they have used recent references to support their study.  The limitations of the study are also given in good depth.  It is also interesting that colorectal cancer screening starts at the age of 50 compared to other parts of the world such as the United states.  This parameter of starting screening at age 50 used to be similar in the United states however it has changed since the last few years.  Perhaps this may also change in the future in Bulgaria with changes in diet and other parameters that may also be occurring there as well.  Perhaps further studies to look into this may be beneficial too.

Author Response

Dear Reviewer,

We would like to express our sincere appreciation for your thoughtful and encouraging comments regarding our manuscript. We are grateful for your recognition of the relevance and importance of this topic for gastroenterologists and the broader healthcare community, as well as for your positive remarks on the study design, the presentation of results, and the discussion and limitations.

We also note with interest your reflections on the age of initiation for colorectal cancer screening and agree that this is an important area for future research.

Once again, we thank you for your valuable feedback.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study is timely and suitable for publication, as it addresses Bulgaria’s recent and much-needed steps toward implementing a national colorectal cancer (CRC) screening program. The authors present important findings on a key public health issue in a country with CRC incidence and mortality rates exceeding the European average. Its originality lies in capturing expert perceptions at a pivotal moment, just before the nationwide rollout, offering valuable insight into professional readiness, systemic barriers, and logistical preferences. Given the demonstrated success of organized screening programs in reducing CRC mortality across Europe, this research provides essential evidence to inform tailored policy development within the Bulgarian healthcare system.

Major points:

Section 2.1 Choice and rationale of screening modalities would be more appropriately placed within the Introduction, as it summarizes existing knowledge rather than presenting study-specific data.

 

Given the national relevance of the study, it would strengthen the manuscript to include information on the geographical distribution of the 400 invited professionals and indicate the regions with higher response rates, as it would help assess the national representativeness of the findings.

The authors acknowledge the low response rate (~10%) and the limited sample size as limitations. However, the sample appears skewed toward younger professionals, which may have influenced the study's findings. The authors should explore this further and discuss its potential impact on the conclusions drawn.

The Discussion lacks clarity and would benefit from improved structure and more concise language. Although it contains substantial information, the narrative is often dense and repetitive, particularly in sections addressing international comparisons and mail-based FIT strategies. Rather than a critical analysis, the current text provides a narrative review of other countries’ practices (e.g., UK, Netherlands, Denmark, Australia). Introducing clear subheadings such as Barriers to FOBT Use, Feasibility of Mail-Based FIT, or International Comparisons would enhance readability and coherence. The current subsection titles add to the confusion rather than guiding the reader. Topics like fear-based barriers and health literacy are only briefly mentioned, while other points are repeated. Smoother transitions between paragraphs would also help avoid the "list-like" feel in parts of the text.

Minor points:

The descriptors of systemic barriers listed in the abstract (lines 24–27) lack context. While scoring is later explained, the abstract should be revised to clarify what these parameters represent.

References are missing for the studies mentioned in lines 398–401 and 433–435 (Greek study), as well as in lines 488–490 (Latvian study).

The source of data presented in lines 474–498 within the Discussion section is unclear and needs clarification.

Acronyms should be consistently introduced upon first mention throughout the manuscript.

Numerical data presentation should be simplified and percentages should be rounded for readability, especially given the small sample size.

Author Response

Dear Reviewer,

We would like to sincerely thank you for your careful review and thoughtful comments on our manuscript. We greatly appreciate your positive assessment of the study’s relevance, originality, and potential contribution to informing national policy on colorectal cancer (CRC) screening in Bulgaria. Your detailed feedback has been invaluable in guiding our revisions, and we have addressed each of your suggestions carefully to strengthen the clarity, structure, and overall quality of the manuscript.

Comments 1: Section 2.1 Choice and rationale of screening modalities would be more appropriately placed within the Introduction, as it summarizes existing knowledge rather than presenting study-specific data.

Response 1: Dear Reviewer, thank you for your valuable comment. We have moved Section 2.1 "Choice and rationale of screening modalities" to the Introduction, as suggested

Comments 2: Given the national relevance of the study, it would strengthen the manuscript to include information on the geographical distribution of the 400 invited professionals and indicate the regions with higher response rates, as it would help assess the national representativeness of the findings.

Response 2: Thank you for this comment. We revised the Results section (3.1 Sociodemographic characteristics) to include information on the geographic distribution of the participating gastroenterologists. This addition can be found in lines 204–208 of the revised manuscript:

“The respondents were distributed across eight cities, with the largest proportion practicing in Plovdiv (44.74%), followed by Sofia (18.42%) and Burgas (15.79%). Smaller numbers of participants were located in Panagyurishte (5.26%), Pleven (5.26%), and Varna (5.26%), while single participants were based in Stara Zagora (2.63%) and Velingrad (2.63%).”

We would like to clarify that we targeted cities with medical universities and university hospitals that provide publicly accessible email addresses. However, since the sample size and response rate are very low, we cannot state that the study is representative, which as included in the manuscript is acknowledged as one of the study’s limitations.

Comments 3: The authors acknowledge the low response rate (~10%) and the limited sample size as limitations. However, the sample appears skewed toward younger professionals, which may have influenced the study's findings. The authors should explore this further and discuss its potential impact on the conclusions drawn.

Response 3: Thank you for this important observation. We recognize that our sample is skewed toward younger professionals, with a mean age of 36.45 years and a median of 34.5 years, and we agree that this demographic profile could have influenced the study’s findings. In the revised manuscript (Limitations section, lines 630-634), we have added a statement explicitly acknowledging this as a limitation:

“Furthermore, the sample was skewed toward younger professionals (mean age 36.45 years), which may have influenced attitudes toward novel approaches such as mail-based screening, as younger specialists may be more receptive to innovation. This demographic profile may therefore limit the generalizability of the findings to the entire gastroenterology workforce.”

Comments 4: The Discussion lacks clarity and would benefit from improved structure and more concise language. Although it contains substantial information, the narrative is often dense and repetitive, particularly in sections addressing international comparisons and mail-based FIT strategies. Rather than a critical analysis, the current text provides a narrative review of other countries’ practices (e.g., UK, Netherlands, Denmark, Australia). Introducing clear subheadings such as Barriers to FOBT Use, Feasibility of Mail-Based FIT, or International Comparisons would enhance readability and coherence. The current subsection titles add to the confusion rather than guiding the reader. Topics like fear-based barriers and health literacy are only briefly mentioned, while other points are repeated. Smoother transitions between paragraphs would also help avoid the "list-like" feel in parts of the text.

Response 4:  

Thank you for this constructive comment. In response, we have carefully revised the Discussion section to improve its clarity, structure, and conciseness. Specifically, we introduced clear and descriptive subheadings to guide the reader through the key themes and improve coherence. The new subheadings include:

• 4.3 Barriers to CRC Screening in Bulgaria
• 4.4 Feasibility of Mail-Based FOBT
• 4.5 Lessons from Successful International Mail-Based FOBT Programs

We further revised the final paragraph of Discussion Section 4.5 (Lessons from Successful International Mail-Based FOBT Programs), enhancing its readability and incorporating analytical insights. The revised paragraph concludes with clear, evidence-based recommendations to support the design and implementation of the forthcoming colorectal cancer screening program in Bulgaria.

We also addressed the concern about transitions between paragraphs and revised them at key points to improve coherence and narrative flow. In addition, we revised the Discussion for greater clarity, structure, and conciseness, reducing repetition while ensuring that all key points are retained.

We also expanded the discussion of fear-related and health literacy barriers, providing specific recommendations on how these issues could be mitigated in future screening efforts.

Lines 421-428:

“These findings underscore the critical role of healthcare professionals not only in delivering patient education and counseling, but also in actively shaping perceptions about colorectal cancer screening. Their involvement is essential to building trust, clarifying the purpose and benefits of early detection, and reducing fear and stigma associated with testing. Moreover, these results emphasize the importance of targeted, culturally appropriate communication strategies aimed at improving health literacy, addressing persistent misconceptions, and promoting CRC screening as a routine and accepted element of preventive healthcare.”

 

Lines 438-443:

“These insights suggest that interventions to reduce fear should focus on empathetic communication by healthcare professionals, providing patients with detailed yet reassuring information about the safety and tolerability of procedures, and offering pre-procedural counseling or support services. Tailored educational materials that demystify CRC and clarify its role in prevention could further mitigate anxiety and promote greater acceptance of screening.”

 

Comments 5:  The descriptors of systemic barriers listed in the abstract (lines 24–27) lack context. While scoring is later explained, the abstract should be revised to clarify what these parameters represent.

Response 5: Thank you for this insightful comment. We agree that the original abstract lacked sufficient context to explain the numerical descriptors of systemic and patient-level barriers. In response, we have revised this section of the abstract to explicitly state that the reported mean values reflect ratings on a 5-point Likert scale. The revised sentence now reads:

“Key systemic barriers, rated on a 5-point Likert scale, included financial constraints (mean = 3.08), inadequate infrastructure (2.89), and healthcare workforce shortages (2.71). Patient-level barriers were led by low health literacy (4.13), lack of motivation (3.95), and procedural fears (3.26).”  

Comments 6: References are missing for the studies mentioned in lines 398–401 and 433–435 (Greek study), as well as in lines 488–490 (Latvian study).

Response 6: Thank you for this comment. We have added the missing reference for the study mentioned in lines 398–401 (now appearing around line 403 in the revised manuscript). Regarding the Greek study referenced in lines 433–435, this citation was already present in the original submission as reference [22]. Similarly, for the Latvian study mentioned in lines 488–490, the appropriate reference was also included in the original manuscript as reference [25]. We have double-checked these citations to ensure accuracy and consistency.

Comments 7: The source of data presented in lines 474–498 within the Discussion section is unclear and needs clarification.

Response 7: Thank you for this comment. In response, we have clarified the source of the information by explicitly attributing it to Goodwin et al. (2019) at the start of the relevant paragraph (now at line 487 in the revised manuscript). The paragraph now reads as follows:

"Building on existing evidence, Goodwin et al. (2019) conducted a systematic review and meta-analysis that identified four key strategies that significantly improve participation in mailed FOBT programs: advance notification, GP endorsement, telephone contact, and simplified testing procedures."

Additionally, in line 502 of the revised manuscript, we explicitly clarified the provenance of the Latvian data by revising the sentence to read:

"Furthermore, a randomized population-based study conducted in Latvia by Santare et al. (2015) demonstrated the influence of invitation strategy and test selection on CRC screening participation."

Comments 8: Acronyms should be consistently introduced upon first mention throughout the manuscript.

Response 8: Dear Reviewer, thank you for your comment. We have carefully revised the manuscript to ensure that all acronyms are consistently introduced upon first mention.

Comments 9: Numerical data presentation should be simplified and percentages should be rounded for readability, especially given the small sample size.

Response 9:  Dear Reviewer, thank you very much for this comment. We fully appreciate the importance of clear and accessible data presentation, particularly in studies with small sample sizes. However, we have chosen to retain the presentation of precise percentages in order to ensure consistency, accuracy, and transparency of reporting. Given the modest sample size (n=38), even small differences can be relevant. We hope this explanation clarifies our rationale, and we remain happy to make further adjustments if needed.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors

Manuscript explains well and an interesting study conducted highlights strong support among Bulgarian gastroenterologists for a national CRC screening program, with particular endorsement of mail-based fecal occult blood testing (FOBT).

The following steps should provide more clear information for readers to enjoy it

Reference section

1) Please add up-to-date references in the introduction and discussion section.

Methods section

2) Statistical analyses – Please keep a subsection in the methods.  

Author Response

Dear Reviewer,

We would like to express our sincere gratitude for your thorough and constructive feedback. We greatly appreciate your positive evaluation of the manuscript and your valuable suggestions, which have contributed to enhancing its clarity and quality.

Comments 1: Please add up-to-date references in the introduction and discussion section.

Response 2: Dear Reviewer, thank you for your comment. We have added up-to-date references from 2024 and 2025.

Comments 2: Statistical analyses – Please keep a subsection in the methods.

Response 2: Dear Reviewer, thank you for your comment. We have added a subheading 2.2 Statistical analysis in the Materials and Methods section.  

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have responded adequately to most comments and improved the clarity of the manuscript.