A 62-year-old woman with a history of chronic atrophic gastritis and pernicious anemia presents with persistent epigastric discomfort and loss of appetite for 3 months. Upper endoscopy shows a 4 cm polypoid lesion in the gastric fundus with central ulceration. Biopsy reveals well-differentiated adenocarcinoma arising from intestinal metaplasia. Immunohistochemistry shows CDX2 positivity. Staging CT reveals no distant metastases, but there is involvement of the gastric wall up to the serosa. Which of the following best describes the pathological sequence that led to this malignancy?