Final answer:
For tumors less than 4cm in renal carcinoma, options like partial nephrectomy or ablation techniques are considered to preserve kidney function.
Step-by-step explanation:
For renal carcinoma, a radical nephrectomy is commonly performed as the surgical treatment, especially for larger tumors. However, when the tumor is less than 4cm, less invasive options may be considered. These options include partial nephrectomy, where only the tumor and a small margin of healthy tissue are removed, and ablation techniques such as radiofrequency ablation or cryoablation that aim to destroy the tumor cells without removing them. The decision between these treatments is based on various factors including tumor location, patient's overall health, and likelihood of preserving kidney function.