Pourquoi certains cancers comme le cancer du rein ont besoin de plus de rayons que d'autres cancers pour être guéris ?
Medical uses

It is estimated that half of the US' 1.2M invasive cancer cases diagnosed in 2022 received radiation therapy in their treatment program. Different cancers respond to radiation therapy in different ways.

The response of a cancer to radiation is described by its radiosensitivity.Highly radiosensitive cancer cells are rapidly killed by modest doses of radiation. These include leukemias, most lymphomas, and germ cell tumors.The majority of epithelial cancers are only moderately radiosensitive, and require a significantly higher dose of radiation (60–70 Gy) to achieve a radical cure.Some types of cancer are notably radioresistant, that is, much higher doses are required to produce a radical cure than may be safe in clinical practice. Renal cell cancer and melanoma are generally considered to be radioresistant but radiation therapy is still a palliative option for many patients with metastatic melanoma. Combining radiation therapy with immunotherapy is an active area of investigation and has shown some promise for melanoma and other cancers.

It is important to distinguish the radiosensitivity of a particular tumor, which to some extent is a laboratory measure, from the radiation "curability" of a cancer in actual clinical practice. For example, leukemias are not generally curable with radiation therapy, because they are disseminated through the body. Lymphoma may be radically curable if it is localized to one area of the body. Similarly, many of the common, moderately radioresponsive tumors are routinely treated with curative doses of radiation therapy if they are at an early stage. For example, non-melanoma skin cancer, head and neck cancer, breast cancer, non-small cell lung cancer, cervical cancer, anal cancer, and prostate cancer. With the exception of oligometastatic disease, metastatic cancers are incurable with radiation therapy because it is not possible to treat the whole body.

Modern radiation therapy relies on a CT scan to identify the tumor and surrounding normal structures and to perform dose calculations for the creation of a complex radiation treatment plan. The patient receives small skin marks to guide the placement of treatment fields. Patient positioning is crucial at this stage as the patient will have to be placed in an identical position during each treatment. Many patient positioning devices have been developed for this purpose, including masks and cushions which can be molded to the patient. Image-guided radiation therapy is a method that uses imaging to correct for positional errors of each treatment session.

The response of a tumor to radiation therapy is also related to its size. Due to complex radiobiology, very large tumors respond less well to radiation than smaller tumors or microscopic disease. Various strategies are used to overcome this effect. The most common technique is surgical resection prior to radiation therapy. This is most commonly seen in the treatment of breast cancer with wide local excision or mastectomy followed by adjuvant radiation therapy. Another method is to shrink the tumor with neoadjuvant chemotherapy prior to radical radiation therapy. A third technique is to enhance the radiosensitivity of the cancer by giving certain drugs during a course of radiation therapy. Examples of radiosensitizing drugs include cisplatin, nimorazole, and cetuximab.

The impact of radiotherapy varies between different types of cancer and different groups. For example, for breast cancer after breast-conserving surgery, radiotherapy has been found to halve the rate at which the disease recurs. In pancreatic cancer, radiotherapy has increased survival times for inoperable tumors.
Radiothérapie

L'utilisation de rayons X à des fins thérapeutiques est connue sous le nom de radiothérapie et est largement utilisée pour la prise en charge (y compris en palliation) du cancer ; elle nécessite des doses de radiation plus élevées que celles reçues pour l'imagerie seule. Des faisceaux de rayons X sont utilisés pour traiter les cancers de la peau avec des faisceaux de rayons X à basse énergie, tandis que des faisceaux à haute énergie sont utilisés pour traiter les cancers à l'intérieur du corps, tels que le cerveau, les poumons, la prostate et le sein.
### Query ###
Pourquoi certains cancers comme le cancer du rein ont besoin de plus de rayons que d'autres cancers pour être guéris ?

### Main Text ###
Medical uses

It is estimated that half of the US' 1.2M invasive cancer cases diagnosed in 2022 received radiation therapy in their treatment program. Different cancers respond to radiation therapy in different ways.

The response of a cancer to radiation is described by its radiosensitivity.Highly radiosensitive cancer cells are rapidly killed by modest doses of radiation. These include leukemias, most lymphomas, and germ cell tumors.The majority of epithelial cancers are only moderately radiosensitive, and require a significantly higher dose of radiation (60–70 Gy) to achieve a radical cure.Some types of cancer are notably radioresistant, that is, much higher doses are required to produce a radical cure than may be safe in clinical practice. Renal cell cancer and melanoma are generally considered to be radioresistant but radiation therapy is still a palliative option for many patients with metastatic melanoma. Combining radiation therapy with immunotherapy is an active area of investigation and has shown some promise for melanoma and other cancers.

It is important to distinguish the radiosensitivity of a particular tumor, which to some extent is a laboratory measure, from the radiation "curability" of a cancer in actual clinical practice. For example, leukemias are not generally curable with radiation therapy, because they are disseminated through the body. Lymphoma may be radically curable if it is localized to one area of the body. Similarly, many of the common, moderately radioresponsive tumors are routinely treated with curative doses of radiation therapy if they are at an early stage. For example, non-melanoma skin cancer, head and neck cancer, breast cancer, non-small cell lung cancer, cervical cancer, anal cancer, and prostate cancer. With the exception of oligometastatic disease, metastatic cancers are incurable with radiation therapy because it is not possible to treat the whole body.

Modern radiation therapy relies on a CT scan to identify the tumor and surrounding normal structures and to perform dose calculations for the creation of a complex radiation treatment plan. The patient receives small skin marks to guide the placement of treatment fields. Patient positioning is crucial at this stage as the patient will have to be placed in an identical position during each treatment. Many patient positioning devices have been developed for this purpose, including masks and cushions which can be molded to the patient. Image-guided radiation therapy is a method that uses imaging to correct for positional errors of each treatment session.

The response of a tumor to radiation therapy is also related to its size. Due to complex radiobiology, very large tumors respond less well to radiation than smaller tumors or microscopic disease. Various strategies are used to overcome this effect. The most common technique is surgical resection prior to radiation therapy. This is most commonly seen in the treatment of breast cancer with wide local excision or mastectomy followed by adjuvant radiation therapy. Another method is to shrink the tumor with neoadjuvant chemotherapy prior to radical radiation therapy. A third technique is to enhance the radiosensitivity of the cancer by giving certain drugs during a course of radiation therapy. Examples of radiosensitizing drugs include cisplatin, nimorazole, and cetuximab.

The impact of radiotherapy varies between different types of cancer and different groups. For example, for breast cancer after breast-conserving surgery, radiotherapy has been found to halve the rate at which the disease recurs. In pancreatic cancer, radiotherapy has increased survival times for inoperable tumors.

### Supplementary Text ###
Radiothérapie

L'utilisation de rayons X à des fins thérapeutiques est connue sous le nom de radiothérapie et est largement utilisée pour la prise en charge (y compris en palliation) du cancer ; elle nécessite des doses de radiation plus élevées que celles reçues pour l'imagerie seule. Des faisceaux de rayons X sont utilisés pour traiter les cancers de la peau avec des faisceaux de rayons X à basse énergie, tandis que des faisceaux à haute énergie sont utilisés pour traiter les cancers à l'intérieur du corps, tels que le cerveau, les poumons, la prostate et le sein.

### Draft ###

Query: "Pourquoi certains cancers comme le cancer du rein ont besoin de plus de rayons que d'autres cancers pour être guéris ?"

→ Translation: Why some cancers like renal cancer need more radiation than others to be cured.

**Key terms:**
- "plus de rayons" = more radiation exposure
- "cancers... nécessitent différentes doses" = cancers require different doses
- "guéris" = cured/healed

**Information retrieval task?** ◐ Partially. Needs biological reasoning.

### 1. Radiobiological Fundamentals

Radiotherapy efficacy ∝ radiosensitivity of cancer cells
- Highly radiosensitive: 2-10 Gy curative
- Moderately radiosensitive: 50-60 Gy curative  
- Radioresistant: >70 Gy often needed

**Physical constraint:** Normal tissue tolerance limits radiation dose. Can't exceed ~2-3 Gy/day for most normal tissues.

∴ Higher radiation requirements often = higher intrinsic resistance.

### 2. Renal Cell Carcinoma Characteristics

● Renal cell cancer = prototypical radioresistant tumor
- Poor response to conventional radiation
- Requires 60-70+ Gy for local control
- Metastatic disease: palliative only

**Why resistant?**
→ Complex genetic profile (VHL, p53 mutations)
→ Enhanced DNA repair pathways
→ Reduced apoptosis induction
→ Hypoxic microenvironment

**Contrast:** Lymphomas, leukemias → very radiosensitive (1-2 Gy kills rapidly)

### 3. Biological Mechanisms

**Radiosensitivity factors:**
├─ Cell cycle phase distribution
├─ DNA repair capacity  
├─ Oxygenation status
└─ Clonogenic survival

⟨H≈0.8⟩ The cancer cell's molecular choreography - repair enzymes dancing around damaged DNA, checkpoints failing, apoptosis machinery rusting in hypoxic shadows. Some cells commit hara-kiri at mere whispers of radiation energy, others shrug off megatonnage like philosophical martyrs...

**Key insight:** Radioresistance ≠ radioinhibition
- High doses eventually kill resistant cells
- But normal tissue tolerance becomes limiting factor
- ⚠ Metastatic disease especially problematic

### 4. Clinical Translation

**Dose-response curves:**
- Curable cancers: steep initial slope → rapid cell death
- Radioresistant cancers: shallow slope → gradual kill

NB: Treatment planning constrained by normal tissue toxicity.

**Modern approaches:**
- Stereotactic ablative body radiotherapy (SABR)
- Hypofractionation protocols  
- Immunotherapy combinations
- Targeted therapy + radiation

### 5. Synthesis

Renal cancer needs more radiation because:

1. **Intrinsic radioresistance** - cellular mechanisms prevent efficient DNA damage response
2. **Treatment window** - must balance tumor control vs normal tissue toxicity  
3. **Genetic heterogeneity** - VHL/p53 pathways disrupt radiation sensitivity
4. **Microenvironmental factors** - hypoxia enhances resistance

**Physical reality check:** Metastatic renal cancer rarely curable regardless of radiation dose due to systemic disease burden.

**Clinical bottom line:** Radioresistant cancers require higher absolute doses, but absolute cure rates may still be limited by other factors (metastases, comorbidities).

∴ "Need more radiation" often reflects underlying biological resistance, not treatable deficiency.

### Answer###
Certains cancers nécessitent plus de radiation que d'autres car leur capacité de réponse aux traitements par rayonnement diffèrent considérablement. Cette différence repose sur ce qu'on appelle la radiosensibilité du cancer.

Les cancers sont classés selon leur réponse au traitement par rayonnement : les cancers très radiosensibles sont rapidement tués par des doses modérées de radiation, ce qui inclut les leucémies, la majorité des lymphomes et les tumeurs germinales. Les cancers épidermoïdes constituent la grande majorité et sont seulement moyennement radiosensibles, nécessitant des doses de radiation significativement plus élevées (60-70 Gy) pour obtenir une guérison radicale.

Le cancer rénal fait partie des cancers notablement radiorésistants, ce qui signifie qu'il nécessite des doses de radiation beaucoup plus importantes pour produire une guérison radicale que ce qui serait cliniquement sécuritaire. Pour ces cancers radiorésistants, même si les traitements conventionnels nécessitent des doses élevées, d'autres options thérapeutiques peuvent être envisagées, notamment en contexte palliatif pour les cancers métastatiques.

Il est important de distinguer la radiosensibilité d'une tumeur particulière, qui est en partie une mesure de laboratoire, de la "guérissabilité" du cancer dans la pratique clinique réelle. Les stratégies thérapeutiques peuvent inclure l'utilisation de médicaments sensibilisateurs à la radiation ou l'association de la radiothérapie avec d'autres traitements comme l'immunothérapie, particulièrement prometteuse pour certains cancers comme le mélanome.