Example sentences:

Ramayana: Ravana’s fall illustrates a universal lesson: when lust is indulged in indiscriminately, it metastasizes till it devastates not just the lusty person but many others connected with that person. 

Mahabharata: Duryodhana’s envy for the Pandavas had metastasized to such a degree that he couldn’t peacefully enjoy his prosperity even after he had reduced them to utter poverty. 

Bhagavad-gita: If we keep giving in to our lower desires, they will metastasize and make it impossible for us to hold on to any higher values.