Question:medium
A patient with a known mutation in the Rb gene is disease free from retinoblastoma. The patient is at highest risk of developing which of the following malignancies?
A patient with a known mutation in the Rb gene is disease free from retinoblastoma. The patient is at highest risk of developing which of the following malignancies?
Show Hint
RB1 carriers face lifelong second cancers, and the commonest one arises in bone.
Updated On: Jun 24, 2026
- Renal cell carcinoma
- Osteosarcoma
- Pinealoblastoma
- Chondrosarcoma
Show Solution
The Correct Option is B
Solution and Explanation
Hereditary retinoblastoma is the classic example of a germline tumour suppressor loss. Because one defective RB1 allele is present in every cell, only a single further mutation is needed to seed a tumour, so these individuals stay at risk for new cancers throughout life even after the eye disease is cured. The question asks which second cancer they are most likely to face.
The well established answer is osteosarcoma. Bone is the leading site of second primary malignancy in retinoblastoma survivors, and the risk climbs higher if the orbit was irradiated, although osteosarcoma also appears outside any radiation field. This consistent association is what makes option B correct.
Pinealoblastoma is a real RB1 link, seen as the third tumour in trilateral retinoblastoma, but it shows up in young children essentially together with the ocular tumours rather than as a later second cancer in a survivor, and it is far rarer than bone sarcoma. Renal cell carcinoma points to the von Hippel-Lindau pathway and is unrelated to RB1. Chondrosarcoma is not a recognised RB1 second tumour. Weighing these together, osteosarcoma carries the highest risk.
\[\boxed{\text{Osteosarcoma}}\]
The well established answer is osteosarcoma. Bone is the leading site of second primary malignancy in retinoblastoma survivors, and the risk climbs higher if the orbit was irradiated, although osteosarcoma also appears outside any radiation field. This consistent association is what makes option B correct.
Pinealoblastoma is a real RB1 link, seen as the third tumour in trilateral retinoblastoma, but it shows up in young children essentially together with the ocular tumours rather than as a later second cancer in a survivor, and it is far rarer than bone sarcoma. Renal cell carcinoma points to the von Hippel-Lindau pathway and is unrelated to RB1. Chondrosarcoma is not a recognised RB1 second tumour. Weighing these together, osteosarcoma carries the highest risk.
\[\boxed{\text{Osteosarcoma}}\]
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