Which of the following is a clinical indicator of breast cancer progression?

Changes in breast tissue serve as a clinical indicator of breast cancer progression because they may indicate the presence of abnormalities that suggest cancerous growth. These changes can manifest as symptoms such as lumps, swelling, skin dimpling, or alterations in the shape or size of the breast. Clinicians often monitor these changes closely as they can be a direct consequence of tumor development and invasiveness, providing critical information for diagnosis and treatment planning.

Increased mammogram frequency, while important for screening, is not a direct clinical indicator of cancer progression; rather, it's a proactive measure to catch potential issues early. Higher exercise levels and improved diet can influence overall health but do not reflect cancer progression; they may contribute to prevention or improved outcomes but are not markers for the status of cancer development.