Nearly half of all cancer deaths could be prevented
Em Coimbra, Portugal, investigadores e profissionais de saúde reuniram-se para examinar uma das afirmações mais consequentes da medicina preventiva contemporânea: que cerca de metade de todas as mortes por cancro no mundo poderiam ser evitadas se as populações seguissem doze recomendações baseadas em décadas de investigação epidemiológica. O Código Europeu Contra o Cancro, agora na sua quarta edição, não oferece revelações isoladas, mas sim o peso acumulado de comportamentos modificáveis — tabaco, obesidade, dieta, álcool, exposição solar, riscos ocupacionais e vacinação — cujo impacto conjunto representa uma transformação possível do sofrimento humano. É um documento que coloca a responsabilidade tanto nos indivíduos como nas sociedades, lembrando que o conhecimento científico só salva vidas quando atravessa a distância entre o papel e a prática.
- Aproximadamente metade das mortes globais por cancro poderia ser prevenida — não com novos medicamentos, mas com mudanças de comportamento já documentadas pela ciência.
- O congresso de Coimbra reuniu os próprios investigadores que desenvolveram o Código Europeu, transformando um seminário de saúde numa revisão rigorosa das evidências disponíveis.
- Temas como a terapia hormonal de substituição e o aleitamento materno revelam que nem todas as recomendações são simples: algumas exigem avaliação individual cuidadosa em vez de orientações universais.
- As vacinas contra a hepatite B e o papilomavírus humano surgem como vitórias preventivas claras, já integradas no calendário vacinal português, demonstrando que a prevenção oncológica pode ser sistematizada.
- O verdadeiro desafio identificado no congresso não é científico, mas de tradução: levar este conhecimento dos artigos de investigação para as mãos de clínicos, decisores de saúde pública e cidadãos dispostos a agir.
Numa sala de conferências em Coimbra, Carlos Oliveira, presidente da delegação Centro da Liga Portuguesa Contra o Cancro, preparava-se para apresentar uma afirmação de peso: quase metade de todas as mortes por cancro no mundo poderiam ser evitadas. O instrumento em causa era o Código Europeu Contra o Cancro, agora na sua quarta edição, resultado de décadas de investigação epidemiológica sobre os comportamentos e exposições que mais influenciam o risco oncológico.
A Liga organizou um congresso de dois dias para percorrer as doze recomendações do Código, com a presença de muitos dos investigadores que contribuíram para a sua elaboração através da Agência Internacional de Investigação sobre o Cancro, o braço de investigação da Organização Mundial de Saúde.
As doze recomendações abrangem território familiar, mas tratado com rigor científico. O tabaco encabeça a lista — incluindo a exposição ao fumo passivo. Seguem-se a obesidade, a atividade física (distinguida do exercício formal, numa diferença que Oliveira sublinhou), a dieta mediterrânica como modelo alimentar de referência, o consumo moderado de álcool, a proteção solar, os riscos ocupacionais e a atenção ao radão em edifícios.
Dois temas geraram menos consenso: o aleitamento materno e o risco de cancro da mama permaneciam em discussão científica, enquanto a terapia hormonal de substituição apresentava um quadro mais complexo, com algumas formulações associadas a um ligeiro aumento do risco, exigindo avaliação individual.
As vacinas contra a hepatite B e o papilomavírus humano representaram uma vitória preventiva inequívoca, já integradas no calendário vacinal português. A última recomendação incidia sobre os programas organizados de rastreio — a identificação sistemática de doença em fase precoce em populações assintomáticas.
O que tornava a afirmação de Oliveira notável não era nenhuma recomendação isolada, mas o seu peso acumulado: se as populações seguissem as doze orientações, os modelos epidemiológicos sugeriam que cerca de metade das mortes por cancro poderiam ser prevenidas. O congresso existia precisamente para encurtar a distância entre esse conhecimento e quem tem o poder de o aplicar.
In a conference room in Coimbra, Portugal, a simple claim was being prepared for public discussion: nearly half of all cancer deaths worldwide could be prevented. The assertion came from Carlos Oliveira, president of the Central branch of the Portuguese League Against Cancer, who pointed to a document that has been refined over decades—the European Code Against Cancer, now in its fourth iteration. The code distills what decades of epidemiological research have learned about which behaviors and exposures drive cancer risk, and which ones we can actually control.
The Portuguese League was hosting a two-day congress on a Friday and Saturday to walk through all twelve of the code's recommendations. The speakers would include many of the researchers who had helped develop the code itself through the International Agency for Research on Cancer, the World Health Organization's research arm. This was not a casual health seminar. It was a deep dive into the evidence.
The twelve points cover familiar territory to anyone who has heard basic health advice, but the code treats them with scientific precision. Tobacco came first—not just active smoking, but secondhand smoke exposure as well. Obesity followed, with particular attention to how excess weight increases the risk of breast cancer in postmenopausal women, as well as prostate and colorectal cancers. Physical activity was listed separately from exercise, a distinction Oliveira emphasized; the code recognizes that movement throughout daily life matters, not just formal workouts.
Diet received substantial attention. The Mediterranean pattern—vegetables, olive oil, whole grains, moderate fish and poultry—emerged as the model to follow. Alcohol consumption was addressed with a recommendation for moderation. Sun exposure warranted protection strategies. Occupational hazards, particularly exposure to carcinogenic substances in workplace settings, were highlighted as an area where Portugal had already implemented considerable legal protections. Radon, the naturally occurring radioactive gas that accumulates in buildings, was flagged as a concern requiring attention.
Two topics generated less consensus. Breastfeeding and breast cancer risk remained an area of ongoing scientific discussion. Hormone replacement therapy for menopausal symptoms presented a more complicated picture—some formulations appeared to slightly elevate breast cancer risk, and the code recommended careful individual evaluation rather than blanket recommendations.
Vaccination represented a clear preventive win. Two vaccines in particular—against hepatitis B and human papillomavirus—had proven effective at preventing cancers caused by these viruses. Both were already part of Portugal's national vaccination schedule. The final recommendation addressed organized screening programs, the systematic identification of early-stage disease in asymptomatic populations.
The European Code Against Cancer itself had emerged from a 1980s European Union initiative called "Europe Against Cancer," born from a recognition that prevention could save more lives than treatment alone. As scientific understanding evolved, the code was updated to reflect new evidence. This fourth edition represented the current state of knowledge about modifiable risk factors—the things people and societies could actually change.
What made Oliveira's claim striking was not that any single recommendation was revolutionary. Rather, it was the cumulative weight: if populations actually followed all twelve guidelines, the epidemiological models suggested that roughly half of cancer deaths could be prevented. That was not a marginal improvement. That was a transformation of the disease's burden. The congress was designed to move that knowledge from research papers into the hands of clinicians, public health officials, and the informed public who would have to decide whether to act on it.
Notable Quotes
Nearly half of cancer deaths in the world could be avoided if the current twelve recommendations of the European Code Against Cancer were followed— Carlos Oliveira, president of the Central branch of the Portuguese League Against Cancer
The Hearth Conversation Another angle on the story
Why frame this as twelve separate recommendations rather than one unified prevention strategy?
Because people live in different circumstances. A factory worker's cancer risk comes partly from occupational exposure; a sunbather's from UV radiation; someone with a family history of breast cancer needs to think differently about hormone therapy. The code lists twelve because prevention isn't one-size-fits-all, even if the underlying principle—reduce modifiable risk—is simple.
The claim is that half of deaths could be prevented. That's enormous. How confident are researchers in that number?
It comes from epidemiological modeling—looking at what fraction of cancers are actually attributable to these twelve factors, then estimating what would happen if exposure dropped to near-zero. The confidence is high for some factors like smoking, lower for others. But the direction is clear: these matter.
Why is the Mediterranean diet singled out when many diets can be healthy?
Because the evidence base is strongest for that pattern. Decades of cohort studies, particularly in Southern Europe, show consistent associations between that way of eating and lower cancer risk. It's not dogma; it's what the data supports.
Breastfeeding and breast cancer risk—you said there's no consensus. What's the disagreement?
The relationship is complex. Some studies suggest breastfeeding slightly reduces a woman's own breast cancer risk, but the effect is modest and the mechanisms aren't fully understood. The code acknowledges the uncertainty rather than making a strong claim either way.
If this code has been around since the 1980s, why is a 2017 conference needed to discuss it?
Because knowing something and acting on it are different things. A code sitting in research literature doesn't change behavior. Bringing clinicians, public health officials, and researchers together to discuss implementation—how to actually get people to follow these guidelines—that's where change happens.