What happens if a squamous cancer goes untreated?

Various developments. If lesion small and cutaneous, then lesion will grow, ulcerate and scab over. If aggressive skin lesion on face or chest wall such lesions rapidly metastasize to region nodes such as those of parotid or axilla and then require radical node dissection. Have seen cases where a chest wall lesion metastatic to axilla required amputation secondary to major vessel involvement.