If i a 35 year old male had peritoneal metastasis how sick would i feel?

On a scale of 0-10 you would feel sick at level greater than 8. You can reduce your risk of cancer by adopting healthy habits: Eat a mostly vegetarian diet, avoid alcohol, tobacco and street drugs, avoid excessive exposure to sun, maintain healthy weight, get HPV vaccine, exercise 30 minutes each day, drink enough water so your urine is mostly colorless. Wish you good health!

Wide range from being completely unaware due to no symptoms to severely sick with multiple symptoms. That makes cancers vicious as they can progress significantly with no or limited perceived symptoms.