A 58-year-old woman with colon cancer presents with 3 months of increasing shoness of breath. A chest X-ray reveals numerous, bilateral, round masses in both lungs. Histologic examination of an open-lung biopsy discloses malignant gland-like structures, which are nearly identical to the colon primary. Which of the following changes in cell behavior was the first step in the process leading to tumor metastasis from the colon to the lung in this patient?
A 58-year-old woman with colon cancer presents with 3 months of increasing shoness of breath. A chest X-ray reveals numerous, bilateral, round masses in both lungs. Histologic examination of an open-lung biopsy discloses malignant gland-like structures, which are nearly identical to the colon primary. Which of the following changes in cell behavior was the first step in the process leading to tumor metastasis from the colon to the lung in this patient?
💡 Explanation
**Core Concept:** Tumor cell dissemination, distant organ colonization, and the process of tumor cell migration from the primary site to the lung.
**Why the Correct Answer is Right:** In this case, the correct answer (D) refers to the first step in the process of tumor cell dissemination from the primary colon cancer site to the lung. This step involves the process of intravasation, where tumor cells enter the bloodstream or lymphatic system from the primary tumor. These cells can then extravasate and survive in the distant organ, such as the lung, where they form colonies and eventually develop into a secondary tumor.
**Why Each Wrong Option is Incorrect:**
A. Angiogenesis (Option A) refers to the growth of new blood vessels around the primary tumor, not the initial step of tumor cell dissemination.
B. Apoptosis (Option B) is the process of programmed cell death, which is the opposite of tumor cell dissemination.
C. Autophagy (Option C) is the process of self-digestion and cellular recycling, not related to tumor cell dissemination.
**Why the Correct Answer is Right:** The correct answer (D) describes the initial step in the process of tumor cell dissemination, which is intravasation. This step involves tumor cells entering the bloodstream or lymphatic system from the primary tumor site. This is a crucial process as it allows these cells to reach the distant organs and form colonies, leading to the development of secondary tumors.
**Clinical Pearl:** The process of tumor cell dissemination is a critical step in the progression of cancer, as it enables cancer cells to spread to other organs and lead to the formation of secondary tumors. Understanding these processes is essential for diagnosing, treating, and managing cancer patients effectively.
✓ Correct Answer: C. Invasion of the underlying basement membrane
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