My weight has been stable for the past 2-3 years (52 kg), but in the past two months, i gained 2 kilos (54 kg). is that normal or could it imply that i have a serious disease?

the 2 kilo weight gain is probably normal and is related to an increase in caloric intake and/or a decrease in physical activity. Malignancies rarely give weight gain, they usually are associated with weight loss. If you feel you haven’t change your habits, a visit to your PCP is in order as some non malignancies, such as thyroid disease can cause weight gain