Investigation of the possible efficacy and safety of lansoprazole co-administration with neoadjuvant chemotherapy in tumor response in women with breast cancer who will be planned for surgery.

Several studies revealed that PPIs inhibit not only the H+/K+ ATPase in gastric parietal cells, but also the vacuolar H+ ATPase (V-ATPase) overexpressed in tumor cells, the V-ATPase is an ATP-dependent proton pump that transports H+ across both intracellular and plasma membranes to regulate intracellular and extracellular pH.

Co-administration or pretreatment with PPIs could inhibit H+ transport via the V-ATPase in tumor cells, resulting in lower extracellular acidification and intracellular acidic vesicles which increase the sensitivity of the tumor cells to the anticancer agents. Moreover, the low extracellular pH induces an increased activity of drug efflux pumps P-glycoprotein (P-gp), which is closely associated with multi-drug resistance (MDR) of tumors. As a consequence, there remains a lower concentration of chemotherapeutic drugs in tumor cells and reduced cytotoxic efficacy, thus restoring the normal extracellular PH will decrease MDR.

Inclusion Criteria:

• Females with age ≥ 18 years old.
• Newly diagnosed breast cancer patients.
• Planned neoadjuvant chemotherapy.

Exclusion Criteria:

• Pregnancy.
• Nursing mothers.
• Active or uncontrolled infection.
• Presence of another malignancies.
• Inadequate blood picture.
• Serum Creatinine more than 1.5 mg /dl.
• AST and ALT more than 2.5 upper limit.
• History of known hypersensitivity to lansoprazole.