BACKGROUND: Hepatocellular carcinoma (HCC) is the fourth most common cancer in the Philippines and is the second leading cause of cancer-related death due to advanced stage at diagnosis in many patients. Advanced HCC commonly has macrovascular invasion such as portal and hepatic veins however, cases that describe tumor extension into the inferior vena cava (IVC) and right atrium (RA) are rare. CASE SUMMARY: We present a case of a 50-year old female with liver cirrhosis from Chronic Hepatitis B infection who presented with shortness of breath. She was diagnosed with HCC based on dynamic enhancement pattern on CT scan with IV contrast and highly elevated alpha- fetoprotein. CT imaging demonstrated hepatic vein invasion with large tumor thrombus extending to the inferior vena cava and right atrium. Patient also had a mild COVID infection. We treated her with modulated radiotherapy targeting the tumor thrombus along with lenvatinib, tenofovir, and apixaban. The COVID infection did not significantly affect the patient's over-all clinical status. CONCLUSION Vascular invasion of HCC into the IVC and RA portends poor prognosis. While there is no consensus on the intervention on these patients, our case may suggest the use of radiotherapy and oral anticoagulation along with lenvatinib to prolong survival and preserve quality of life.