Cáncer de Ano

¿QUÉ ES EL CÁNCER DE ANO?

El cáncer abarca un conjunto de enfermedades en las cuales las células normales del cuerpo pierden la capacidad de controlar su crecimiento por medio de una serie de cambios genéticos.A medida que avanzan, los cánceres invaden los tejidos que los rodean (invasión local). También pueden extenderse a otros lugares del cuerpo por medio de los vasos sanguíneos o canales linfáticos donde pueden implantarse y desarrollarse (metástasis).

El canal anal es un conducto que conecta el recto con el exterior del cuerpo.Está rodeado de músculos que lo mantienen cerrado excepto cuando se relajan durante la defecación.El cáncer de ano surge de las células de la piel que rodean la abertura del ano o en el canal anal dentro de dicha abertura. Los cánceres de ano surgen de las células de la piel y se denominan carcinomas espinocelulares. Las células que se están transformando en malignas pero que no han invadido la piel con profundidad se denominan “displasia de alto grado”, “carcinoma in situ” o “enfermedad de Bowen”.

¿CUÁLES LA FRECUENCIA DEL CÁNCER DE ANO?

El cáncer de ano es poco común. Representa del 1 al 2% aproximadamente de lo cánceres gastrointestinales. En los Estados Unidos, se diagnostican unos 4,000 casos nuevos de cáncer al año; cerca de la mitad, en mujeres. Unas 600 personas mueren debido a esta enfermedad cada año. Esto puede compararse con los 140,000 casos nuevos de cáncer colorrectal que ocasiona 50,000 muertes al año.

¿QUIÉN TIENE RIESGO?

Por lo general, el cáncer de ano se asocia con el virus del papiloma humano (VPH). Este virus produce verrugas dentro y alrededor del ano y en el cuello del útero. Se asocia con un riesgo mayor de cáncer cervical en las mujeres.

El factor de riesgo es lo que aumenta las probabilidades de que una persona contraiga una enfermedad. Además de la exposición al virus del papiloma humano, existen otros factores de riesgo:

  • Edad: la mayoría de las personas con cáncer de ano son mayores de 50 años.

  • Sexo anal: tienen un riesgo mayor las personas que practican sexo anal.

  • Tabaquismo: las sustancias químicas peligrosas del tabaco aumentan el riesgo de la mayoría de los cánceres, incluso el cáncer de ano.

  • Inmunodepresión: tienen un riesgo mayor las personas con sistemas inmunitarios débiles; tal es el caso de los pacientes de trasplantes que deben tomar fármacos para suprimir sus sistemas inmunitarios, y los pacientes infectados con VIH (virus de inmunodeficiencia humana).

  • Inflamación local crónica: tienen un riesgo ligeramente mayor las personas que durante largo tiempo tienen fístulas anales o heridas abiertas.

  • Radiación pélvica: tienen un riesgo mayor las personas que han recibido terapia de radiación pélvica para cáncer de recto, próstata, vejiga o cuello del útero.

¿PUEDE PREVENIRSE EL CÁNCER DE ANO?

Existen pocos cánceres que pueden prevenirse totalmente; sin embargo, el riesgo que usted tenga puede disminuir considerablemente reduciendo sus factores de riesgo y llevando a cabo revisiones médicas periódicas.Evite el sexo anal y las infecciones de VPH y VIH.Use condones cuando tenga cualquier tipo de relación sexual. Aunque los condones no eliminan el riesgo de infección, lo reducen.Dejar de fumar disminuye el riesgo de muchos tipos de cáncer, incluido el cáncer de ano.

Los exámenes de detección del cáncer de ano pueden realizarse en las personas que tienen alto riesgo.La detección del cáncer de ano puede incluir la prueba de Papanicolau anal o anoscopia.El Papanicolau anal es el mismo tipo de prueba que se usa para detectar el cáncer cervical en la mujer.Se introduce un hisopo en el canal anal, y las células que se extraen al sacarlo se examinan en microscopio.La anoscopia es la evaluación del canal anal con un aparato de observación especial que permite al médico examinar visualmente el revestimiento del canal anal.Las personas que obtienen resultados anormales en el Papanicolau anal deben realizarse una anoscopia de seguimiento para examinar el canal anal.

Las personas que tienen un riesgo mayor deben hablar con el médico acerca de la detección del cáncer de ano. Entre quienes tienen un riesgo particularmente alto se incluyen los hombres portadores del VIH, hombres que tienen relaciones sexuales con otros hombres, las personas que tienen varias parejas sexuales y las mujeres con antecedentes de verrugas cervicales o a quienes se les haya detectado cambios precancerosos en el cuello del útero.

¿CUÁLES SON LOS SINTOMAS DE CÁNCER DE ANO?

Muchos casos de cáncer de ano pueden detectarse en etapa temprana. Los cánceres de ano se forman en una parte del conducto digestivo que el doctor puede ver y alcanzar con facilidad. Con frecuencia causan síntomas tales como: 

  • Hemorragia del recto o del ano

  • Sensación de un bulto o masa en la abertura del ano

  • Dolor en la zona del ano

  • Comezón persistente o recurrente

  • Cambio en los hábitos de defecación (defecar con mayor o menor frecuencia) o mayor esfuerzo al defecar

  • Heces más angostas

  • Secreción (moco o pus) del ano

  • Ganglios linfáticos (glándulas) hinchadas en las zonas del ano y la ingle

Estos síntomas pueden deberse también a problemas menos graves como hemorroides, pero nunca debe suponerse esto. Si tiene algunos de estos síntomas, acuda al médico.

¿CÓMO SE DIAGNOSTICA EL CÁNCER DE ANO?

Si se obtienen resultados anormales en una prueba de Papanicolau anal, o si se presentan síntomas, es necesario realizar un examen del canal anal. Si el examen del médico identifica una zona anormal, debe realizarse una biopsia para determinar el diagnóstico.Si se confirma un diagnóstico de cáncer, pueden recomendarse pruebas adicionales para determinar la extensión del cáncer.

¿CÓMO SE TRATA EL CÁNCER DE ANO?

Existen tratamientos muy eficaces para la mayoría de los casos de cáncer de ano.Se usan tres tipos básicos de tratamiento:

  • cirugía: una operación para extirpar el cáncer;

  • terapia de radiación: una dosis alta de rayos x para eliminar las células cancerosas; y

  • quimioterapia: fármacos para eliminar células cancerosas.

Actualmente, se considera una terapia de combinación que incluye terapia de radiación y quimioterapia como el tratamiento estándar para la mayoría de los cánceres de ano. En ocasiones, un tumor muy pequeño o en etapa muy temprana se puede extirpar mediante cirugía (extirpación local), con un daño mínimo a los músculos del esfínter anal.

¿NECESITARÉ UNA COLOSTOMIA?

La mayoría de los pacientes que reciben tratamiento para el cáncer de ano no necesitan colostomía. Si el tumor no responde totalmente a la terapia de combinación, o si vuelve a aparecer después del tratamiento, puede ser necesario extirpar el recto y el ano, y crear una colostomía. Esta operación se conoce como resección abdominoperineal (RAP).

¿QUÉ SUCEDE DESPUÉS DEL TRATAMIENTO PARA EL CÁNCER DE ANO?

Es muy importante recibir atención de seguimiento para evaluar los resultados del tratamiento o para verificar si hay recurrencia.La mayoría de los carcinomas de ano se tratan con eficacia. Además, muchos tumores recurrentes pueden tratarse con éxito si se detectan a tiempo.El método más importante de seguimiento es el examen detallado y periódico de un médico con experiencia. Se pueden recomendar estudios adicionales.Usted debe informar de inmediato al médico de cualquier síntoma o problema.

CONCLUSION

Los cánceres de ano son tumores poco comunes que surgen de la piel o revestimiento mucoso del canal anal. Como con la mayoría de los cánceres, se logra una supervivencia excelente con una detección temprana. La mayoría de los tumores se tratan bien con una combinación de quimioterapia y radiación. Por lo general, las recurrencias pueden tratarse con éxito. Siga las recomendaciones de exámenes de detección del cáncer de ano y colorrectal, y consulte al médico lo antes posible cuando se presente cualquier síntoma anorrectal.

AVISO LEGAL

La Asociación Americana de Cirujanos de Colon y Recto está dedicada a asegurar la atención al paciente de alta calidad, al avance de la ciencia, la prevención y el tratamiento de los trastornos y enfermedades del colon, recto y ano.  El propósito de estos folletos es proporcionar información sobre los procesos de enfermedades, y no la de indicar una forma específica de tratamiento. Están diseñados para el uso de  los médicos, trabajadores sanitarios y pacientes que deseen información sobre la gestión de las condiciones tratadas. Estos folletos no incluyen o excluyen otros métodos apropiados de atención médica de estas enfermedades. La última palabra sobre el tratamiento a seguir le corresponde al médico basándose en las circunstancias  de cada paciente.



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