Perioperative chemotherapy (CHT) or CHT/RT combined with surgery is the standard therapeutic approach for the treatment of locally advanced cancer of the esophagus, gastroesophageal junction (GEJ), and stomach. Comprehensive cancer treatment is associated with high perioperative morbidity and mortality. Serious postoperative complications occur in up to 20-80% of patients undergoing esophagectomy. The impact of nutritional status and overall physical condition on surgical outcomes and overall treatment has been demonstrated many times. The concept of pre-rehabilitation/pre-optimization, which involves establishing an individualized nutritional plan, monitoring and managing physical activity, and providing comprehensive supportive oncological and psychological care as early as during neoadjuvant CHT or CHT/RT, is a prerequisite for improving perioperative and 30-day postoperative morbidity and mortality.

Standard care for locally advanced diseases includes perioperative chemotherapy or preoperative chemoradiotherapy, which can, in turn, lead to patient deconditioning prior to surgery. Efforts to overcome these complications led to the development of the ERAS (Enhanced Recovery After Surgery) program. This program overlaps with the emerging concept of prehabilitation/pre-optimization, which is based on identifying risk factors, formulating nutritional support, creating an exercise plan to improve overall physical fitness, and implementing continuous psychological support to enhance the patient's postoperative recovery.

The autonomic nervous system (ANS) is the body's primary homeostatic regulatory system, which can be negatively affected by anticancer treatment. Heart rate variability (HRV) is a suitable candidate for monitoring ANS function and can provide early indication of a deterioration in the sympathovagal balance of test subjects. As mentioned above, preoperative chemotherapy may further affect ANS function. It is known that regimens based on oxaliplatin and paclitaxel cause peripheral neuropathy and are associated with a significant impact on the adrenergic cardiovascular response and parasympathetic cardiac innervation. We hypothesize that a controlled increase in physical cardiorespiratory fitness during the preoperative period could improve HRV and aerobic performance, taking into account the patient's current condition. An integral part of a comprehensive program should also be perioperative individualized nutritional support aimed at maintaining body weight and muscle mass. The most common adverse effects of cancer treatment include cardiac toxicity, peripheral neuropathy, cachexia, loss of appetite, cognitive changes, fatigue, nausea, pain, and sleep disturbances, which have a significant impact on patients' quality of life. For this reason, special attention must also be paid to psychological support during active cancer treatment and in follow-up care. Psychological assessment should serve as a long-term tool for patients and families both during and after the active treatment course. Considering all the above aspects, a comprehensive assessment prior to treatment initiation and a specialized comprehensive program should be approached as a prehabilitation process. Furthermore, this concept, together with ERAS and six-month postoperative follow-up, constitutes optimal management of patients with esophageal cancer.

Inclusion Criteria:

• Consent to participate in the study
• Age ≥ 18 years
• Patients with locally advanced esophageal or gastric cancer indicated for comprehensive perioperative treatment
• Resectable disease
• ECOG performance status 0-2
• Ability to participate in a fitness program
• Willingness to follow a nutritional plan and recommendations

Exclusion Criteria:

• Disseminated disease

IPD to be shared in pseudonymized form during the study. IPD to be published in anonymized form.

after study completion

During the study, data will be managed in pseudonymized form in a protected database environment, available only for study team.

After completion of the study, the data will be fully anonymized for publication purposes. All publication outputs of the study will be carried out by a team of researchers led by the principal investigator. The submission of each publication is subject to the approval of the principal investigator.

The results of this study may be published or presented at scientific meetings after approval by the PI and always after anonymization of the subjects' personal data in accordance with Act No. 101/2000 Coll., on the protection of personal data.